Interpregnancy Interval and Childbirth Outcomes in California, 2007-2009

The association between interpregnancy intervals and preterm birth: a systematic review and meta-analysis

BACKGROUND

Research has shown a relationship between interpregnancy intervals (IPIs) and preterm birth, but a comprehensive understanding remains elusive. The aim of this systematic review and meta-analysis was to examine the effect of different IPIs on the risk of preterm birth METHODS: Systematic searches were conducted in PubMed, Cochrane, Web of Science, and Embase up to June 2, 2023. Studies included in the review provided data on IPIs and preterm birth outcomes, assessed via the NOS quality scale. A Bayesian network meta-analysis was performed to evaluate the association between IPIs and preterm birth.

RESULTS

From 34 studies and 8,646,679 individuals, the optimal IPIs were found to be 24-29 months, showing significantly lower risks of preterm birth at less than 32 weeks of gestation [OR=0.55 (95%CI: 0.50 - 0.62)]and at less than 37 weeks of gestation[OR=0.61 (95%CI: 0.59 - 0.63)]compared to IPIs less than 5 months.

CONCLUSIONS

IPIs of 24-29 months significantly reduce the risk of preterm birth, suggesting a potential target range for family planning and clinical recommendations.

TRIAL REGISTRATION

Not applicable.

Interpregnancy interval, air pollution, and the risk of low birth weight: a retrospective study in China

BACKGROUND

Both interpregnancy intervals (IPI) and environmental factors might contribute to low birth weight (LBW). However, the extent to which air pollution influences the effect of IPIs on LBW remains unclear. We aimed to investigate whether IPI and air pollution jointly affect LBW.

METHODS

A retrospective cohort study was designed in this study. The data of birth records was collected from the Jiangsu Maternal Child Information System, covering January 2020 to June 2021 in Nantong city, China. IPI was defined as the duration between the delivery date for last live birth and date of LMP for the subsequent birth. The maternal exposure to ambient air pollutants during pregnancy-including particulate matter (PM) with an aerodynamic diameter of ≤ 2.5 μm (PM2.5), PM10, ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2) and carbon monoxide (CO)-was estimated using a hybrid kriging-LUR-RF model. A novel air pollution score was proposed, assessing combined exposure to five pollutants (excluding CO) by summing their concentrations, weighted by LBW regression coefficients. Multivariate logistic regression models were used to estimate the effects of IPI, air pollution and their interactions on LBW. Relative excess risk due to interaction (RERI), attributable proportion of interaction (AP) and synergy index (S) were utilized to assess the additive interaction.

RESULTS

Among 10, 512 singleton live births, the LBW rate was 3.7%. The IPI-LBW risk curve exhibited an L-shaped pattern. The odds ratios (ORs) for LBW for each interquartile range increase in PM2.5, PM10, O3 and the air pollution score were 1.16 (95% CI: 1.01-1.32), 1.30 (1.06-1.59), 1.22 (1.06-1.41), and 1.32 (1.10-1.60) during the entire pregnancy, respectively. An additive interaction between IPI and PM2.5 was noted during the first trimester. Compared to records with normal IPI and low PM2.5 exposure, those with short IPI and high PM2.5 exposure had the highest risk of LBW (relative risk = 3.53, 95% CI: 1.85-6.49, first trimester).

CONCLUSION

The study demonstrates a synergistic effect of interpregnancy interval and air pollution on LBW, indicating that rational birth spacing and air pollution control can jointly improve LBW outcomes.

Parental Perceptions of Counseling Regarding Interpregnancy Interval after Stillbirth or Neonatal Death

OBJECTIVE

Although guidelines exist regarding optimal interpregnancy interval (IPI) after live birth, both optimal IPI and counseling regarding recommended IPI (rIPI) after stillbirth or neonatal death is not well established. Our goal was to describe the counseling bereaved parents receive regarding IPI, parents' reactions to that counseling, and actual IPI after loss.

STUDY DESIGN

Bereaved parents who had a previous pregnancy result in stillbirth or neonatal death participated in a web-based survey. Questions included demographics, details of stillbirth or neonatal death, IPI counseling, and pregnancy after loss. Demographic information, rIPI, and ac'tual IPI were reported using descriptive statistics. The Wilcoxon's rank sum test was used to test the association between rIPI and mode of delivery. The Spearman's correlation was used to test the association between rIPI and maternal age.

RESULTS

A total of 275 surveys were analyzed. Mean gestational age of stillbirth delivery was 33.1 (standard deviation: 6.6) weeks. A total of 29% delivered via cesarean. Median rIPI was 6 (interquartile ratio [IQR]: 2-9) months, with the primary reason for IPI reported as the need to heal (74%). Delivery via cesarean was associated with longer rIPI, 9 versus 4.2 months (p < 0.0001). Maternal age was not associated with rIPI. Of 144 people who pursued pregnancy again, median time until attempting conception was 3.5 (IQR: 2-6) months. Median actual IPI was 6 (IQR: 4-10) months.

CONCLUSION

Bereaved parents receive a wide range of counseling regarding rIPI. The majority receive rIPI and pursue actual IPI shorter than current national and international recommendations for optimal IPI.

KEY POINTS

· There is variation in IPI recommendation after stillbirth/neonatal death.. · Cesarean birth is associated with longer IPI recommendation, but maternal age is not.. · Median IPI after stillbirth or neonatal death was short: 6 (IQR: 4-10) months..

Short Interpregnancy Intervals Among Women Experiencing Homelessness in Colorado

Importance

Short interpregnancy intervals (SIPIs) are associated with increased risk of adverse maternal and neonatal outcomes. Disparities exist across socioeconomic status, but there is little information on SIPIs among women experiencing homelessness.

Objective

To investigate (1) differences in rates and characteristics of SIPIs between women experiencing homelessness and domiciled women, (2) whether the association of homelessness with SIPIs differs across races and ethnicities, and (3) whether the association between SIPIs of less than 6 months (very short interpregnancy interval [VSIPIs]) and maternal and neonatal outcomes differs between participant groups.

Design, Setting, and Participants

This cohort study used a Colorado statewide database linking the Colorado All Payer Claims Database, Homeless Management Information System, death records, and infant birth records. Participants included all women who gave birth between January 1, 2016, and December 31, 2021. Data were analyzed from September 1, 2022, to May 10, 2023.

Exposures

Homelessness and race and ethnicity.

Main Outcomes and Measures

The primary outcome consisted of SIPI, a binary variable indicating whether the interval between delivery and conception of the subsequent pregnancy was shorter than 18 months. The association of VSIPI with maternal and neonatal outcomes was also tested.

Results

A total of 77 494 women (mean [SD] age, 30.7 [5.3] years) were included in the analyses, of whom 636 (0.8%) were women experiencing homelessness. The mean (SD) age was 29.5 (5.4) years for women experiencing homelessness and 30.7 (5.3) years for domiciled women. In terms of race and ethnicity, 39.3% were Hispanic, 7.3% were non-Hispanic Black, and 48.4% were non-Hispanic White. Associations between homelessness and higher odds of SIPI (adjusted odds ratio [AOR], 1.23 [95% CI, 1.04-1.46]) were found. Smaller associations between homelessness and SIPI were found among non-Hispanic Black (AOR, 0.59 [95% CI, 0.37-0.96]) and non-Hispanic White (AOR, 0.57 [95% CI, 0.39-0.84]) women compared with Hispanic women. A greater association of VSIPI with emergency department visits and low birth weight was found among women experiencing homelessness compared with domiciled women, although no significant differences were detected.

Conclusions and Relevance

In this cohort study of women who gave birth from 2016 to 2021, an association between homelessness and higher odds of SIPIs was found. These findings highlight the importance of conception management among women experiencing homelessness. Racial and ethnic disparities should be considered when designing interventions.

Association between interpregnancy interval and gestational diabetes mellitus: A cohort study of the National Vital Statistics System 2020

OBJECTIVE

To assess the association between interpregnancy interval (IPI) and gestational diabetes mellitus (GDM).

METHODS

Data of this retrospective cohort study were obtained from the National Vital Statistics System (NVSS) 2020. The participants were divided into different groups according to different IPI (<6, 6-11, 12-17, 18-23, 24-59 (reference), 60-119, ≥120 months). Multivariate logistic models were constructed to evaluate the association between IPI and GDM. Subgroup analysis was further performed.

RESULTS

A total of 1 515 263 women were included, with 123 951 (8.18%) having GDM. Compared with the 24-59 months group, the <6 months (odds ratio [OR] 0.64, 95% confidence interval [CI] 0.46-0.90, P = 0.009), 12-17 months (OR 0.96, 95% CI 0.94-0.98, P < 0.001), and 18-23 months (OR 0.94, 95% CI 0.93-0.96, P < 0.001) groups had a significantly lower risk of GDM, while the 60-119 months (OR 1.13, 95% CI 1.11-1.15, P < 0.001) and ≥120 months (OR 1.18, 95% CI 1.15-1.21, P < 0.001) groups had a significantly higher risk of GDM. No significant difference was observed in the risk of GDM between the 6-11 and 24-59 months groups (P = 0.542). The PI-GDM association varied across different groups of age, pre-pregnancy body mass index, pre-pregnancy smoking status, history of cesarean section, history of preterm birth, prior terminations, and parity.

CONCLUSION

An IPI of 18-23 months may be a better interval than 24-59 months in managing the risk of GDM.

Interactions between long interpregnancy interval and advanced maternal age on neonatal outcomes

BACKGROUND

After the implementation of the universal two-child policy in China, it was more frequent to have long interpregnancy intervals (IPIs) and advanced maternal age. However, the interactions between long IPIs and advanced maternal age on neonatal outcomes are unknown.

METHODS

The study subjects of this historical cohort study were multiparas with singleton live births between October 1st, 2015, and October 31st, 2020. IPI was defined as the interval between delivery and conception of the subsequent pregnancy. Logistic regression models were used to calculate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) of the risks of preterm birth (PTB), low birth weight (LBW), small for gestation age, and 1-min Apgar score ≤ 7 in different IPI groups. Relative excess risk due to interaction (RERI) was used to evaluate the additive interaction between long IPIs and advanced maternal age.

RESULTS

Compared with the 24 ≤ IPI ≤ 59 months group, the long IPI group (IPI ≥ 60 months) was associated with a higher risk of PTB (aOR, 1.27; 95% CI: 1.07-1.50), LBW (aOR, 1.32; 95% CI 1.08-1.61), and one-minute Apgar score ≤ 7 (aOR, 1.46; 95% CI 1.07-1.98). Negative additive interactions (all RERIs < 0) existed between long IPIs and advanced maternal age for these neonatal outcomes. Meanwhile, IPI < 12 months was also associated with PTB (aOR, 1.51; 95% CI 1.13-2.01), LBW (aOR, 1.50; 95% CI 1.09-2.07), and 1-min Apgar score ≤ 7 (aOR, 1.93; 95% CI 1.23-3.04).

CONCLUSIONS

Both short and long IPIs are associated with an increased risk of adverse neonatal outcomes. Appropriate IPI should be recommended to women planning to become pregnant again. In addition, better antenatal care might be taken to balance the inferiority of advanced maternal age and to improve neonatal outcomes.

Birth spacing and risk of adverse pregnancy and birth outcomes: A systematic review and dose-response meta-analysis

INTRODUCTION

The association between extreme birth spacing and adverse outcomes is controversial, and available evidence is fragmented into different classifications of birth spacing.

MATERIAL AND METHODS

We conducted a systematic review of observational studies to evaluate the association between birth spacing (i.e., interpregnancy interval and interoutcome interval) and adverse outcomes (i.e., pregnancy complications, adverse birth outcomes). Pooled odds ratios (ORs) with 95% confidence intervals (CI) were calculated using a random-effects model, and the dose-response relationships were evaluated using generalized least squares trend estimation.

RESULTS

A total of 129 studies involving 46 874 843 pregnancies were included. In the general population, compared with an interpregnancy interval of 18-23 months, extreme intervals (<6 months and ≥ 60 months) were associated with an increased risk of adverse outcomes, including preterm birth, small for gestational age, low birthweight, fetal death, birth defects, early neonatal death, and premature rupture of fetal membranes (pooled OR range: 1.08-1.56; p < 0.05). The dose-response analyses further confirmed these J-shaped relationships (pnon-linear  < 0.001-0.009). Long interpregnancy interval was only associated with an increased risk of preeclampsia and gestational diabetes (pnon-linear  < 0.005 and pnon-linear  < 0.001, respectively). Similar associations were observed between interoutcome interval and risk of low birthweight and preterm birth (pnon-linear  < 0.001). Moreover, interoutcome interval of ≥60 months was associated with an increased risk of cesarean delivery (pooled OR 1.72, 95% CI 1.04-2.83). For pregnancies following preterm births, an interpregnancy interval of 9 months was not associated with an increased risk of preterm birth, according to dose-response analyses (pnon-linear  = 0.008). Based on limited evidence, we did not observe significant associations between interpregnancy interval or interoutcome interval after pregnancy losses and risk of small for gestational age, fetal death, miscarriage, or preeclampsia (pooled OR range: 0.76-1.21; p > 0.05).

CONCLUSIONS

Extreme birth spacing has extensive adverse effects on maternal and infant health. In the general population, interpregnancy interval of 18-23 months may be associated with potential benefits for both mothers and infants. For women with previous preterm birth, the optimal birth spacing may be 9 months.

Interpregnancy Interval After Stillbirth and Adverse Perinatal Outcomes

We used a retrospective cohort of 5,581 individuals to examine the association between interpregnancy interval (IPI) after stillbirth and pregnancy outcomes of preterm birth, preeclampsia, small for gestational age, recurrent stillbirth, infant death, and neonatal intensive care unit admission in the subsequent pregnancy. The IPI was divided in six categories, with 18-23 months as referent. Association between IPI category and adverse outcomes was determined with logistic regression models adjusted for maternal race and ethnicity, age, education, insurance, and gestational age at preceding stillbirth. Adverse perinatal outcome was common in pregnancies after stillbirth, with 26.7% of individuals delivering preterm. None of the IPI categories were associated with increased risk of adverse perinatal outcomes, including the shortest category (IPI less than 3 months). This finding is meaningful for bereaved parents who desire to conceive shortly after stillbirth.

The effects of birth spacing on early childhood development in high-income nations: A systematic review

Objective

This study aimed to systematically review the literature on the associations between birth spacing and developmental outcomes in early childhood (3-10 years of age). Studies examining the associations between interpregnancy intervals and child development outcomes during and beyond the perinatal period have not been systematically reviewed.

Methods

We searched Ovid/MEDLINE, Global Health, PsycINFO, EMBASE, CINAHL Plus, Educational Source, Research Starters, ERIC, Scopus, PubMed, Social Science Research Network database, and ProQuest's Social Sciences Databases for relevant articles published between 1 January 1989 and 25 June 2021. Studies published in English, conducted in populations residing in high-income countries with any measure of birth spacing, and child development outcomes among children aged <10 years were included. Two authors independently assessed the eligibility of studies and extracted data on the study design, setting and population, birth spacing, outcomes, and results.

Results

The search yielded 1,556 records, of which seven studies met the inclusion criteria. Five of these seven studies used birth intervals as the exposure measure. Definitions of exposure differed between the studies. Three studies reported an association between short birth spacing and poorer child development outcomes, and two studies reported an association between long birth spacing and poorer child development outcomes.

Conclusion

Currently, limited evidence suggests that the adverse effects of sub-optimal birth spacing are observable beyond infancy.

Association of Interpregnancy Interval With Adverse Birth Outcomes

IMPORTANCE

Many studies have reported an association of interpregnancy interval (IPI) between 2 consecutive births with adverse birth outcomes in low- and middle-income countries. However, most of these studies ignore the implications of some unmeasured confounders.

OBJECTIVE

To explore the association of IPI with adverse perinatal outcomes.

DESIGN, SETTING, AND PARTICIPANTS

This large-scale cohort study used the Guangdong Provincial Women and Children Health Information System in Guangdong Province, China, to obtain birth data recorded between January 1, 2014, and December 31, 2020. Matched-sibling design was used. The final cohort included first-born and second-born sibling pairs delivered by mothers who were permanent residents of Guangdong Province.

EXPOSURES

The exposure variable was IPI, which was categorized as follows: less than 6, 6 to 11, 12 to 17, 18 to 23, 24 to 29, 30 to 35, and 36 or more months.

MAIN OUTCOMES AND MEASURES

The outcome variables were adverse birth outcomes: preterm birth (PTB, gestational age <37 weeks), low birth weight (LBW, <2500 g), and small for gestational age (SGA). Adjusted odds ratio (OR) and interaction odds ratio (IOR) associated with IPI were calculated.

RESULTS

The study consisted of 725 392 sibling pairs of multiparous mothers. Among these mothers, 718 111 (99.0%) were aged 20 to 34 years, and 715 583 (98.7%) were of Han Chinese ethnicity. Unmatched analysis showed that a short IPI of less than 6 months was associated with higher risks of PTB (adjusted OR, 1.96; 95% CI, 1.87-2.06), LBW (adjusted OR, 1.88; 95% CI, 1.79-1.98), and SGA (adjusted OR, 1.34; 95% CI, 1.30-1.38) compared with an IPI of 18 to 23 months. These associations were attenuated in the matched-sibling analysis. An association of short IPI (<6 months) with PTB (adjusted IOR, 1.40; 95% CI, 1.30-1.51), LBW (adjusted IOR, 1.30; 95% CI, 1.21-1.40), and SGA (adjusted IOR, 1.16; 95% CI, 1.11-1.22) remained in the matched analysis. For IPI of 36 months or more, the odds of PTB (adjusted OR, 1.08; 95% CI, 1.03-1.14) and LBW (adjusted OR, 1.13; 95% CI, 1.07-1.19) in the unmatched analysis were also greater than the reference interval (18-23 months), but not for SGA (adjusted OR, 0.96; 95% CI, 0.93-0.99). Associations between a long IPI (≥36 months) and PTB (adjusted IOR, 1.10; 95% CI, 1.02-1.19) and LBW (adjusted IOR, 1.16; 95% CI, 1.07-1.26) remained through the sibling comparisons.

CONCLUSIONS AND RELEVANCE

Results of this study indicated that mothers with a short (<6 months) or long (≥36 months) IPI had greater odds of adverse birth outcomes. The findings may inform family planning policies and guide individuals and families who are planning for another pregnancy in China.

Perinatal Loss: The Impact on Maternal Mental Health

Importance

Psychological reactions to perinatal loss, although often self-limited, may lead to significant psychological morbidities. Obstetrician-gynecologists and other maternal health providers play a key role in recognizing the range of psychological responses to perinatal loss and providing education, support, and treatment options to their patients.

Objective

This review aims to define psychological reactions associated with perinatal loss, examine psychotherapy and psychopharmacologic treatments for psychiatric morbidities, discuss interpregnancy interval following perinatal loss, and highlight brief, psychological interventions that can be implemented by maternal health providers.

Evidence Acquisition

Search terms "perinatal loss psychology," "reproductive loss grief," "perinatal psychopharmacology," "psychopharmacology grief," and "interpregnancy interval" were utilized to search PubMed, Google Scholar, and PsycINFO.

Results

Grief is an expected, normal response to perinatal loss. Psychological morbidities, including major depressive disorder, generalized anxiety disorder, and posttraumatic stress disorder, are also associated with perinatal loss. Risk factors for these conditions include history of a psychiatric illness, childlessness, unknown cause of perinatal loss, limited social support, and marital/relationship discord. Careful interviewing and brief screening measures can help identify patients who may suffer from depressive or anxiety disorders following reproductive loss. Patients with perinatal loss can benefit from psychological and possibly pharmacologic treatments. Recommended interpregnancy interval after perinatal loss should be customized by gestational age and cause of loss.

Conclusions and Relevance

Patients with perinatal loss emotionally benefit from their reproductive health care providers acknowledging the psychological aspects of reproductive loss, inquiring about their emotional needs, and providing information regarding grief and mental health referrals.

Interpregnancy intervals and child development at age 5: a population data linkage study

OBJECTIVE

To investigate the associations between interpregnancy intervals (IPIs) and developmental vulnerability in children's first year of full-time school (age 5).

DESIGN

Retrospective cohort study using logistic regression. ORs were estimated for associations with IPIs with adjustment for child, parent and community sociodemographic variables.

SETTING

Western Australia (WA), 2002-2015.

PARTICIPANTS

34 574 WA born singletons with a 2009, 2012 or 2015 Australian Early Development Census (AEDC) record.

MAIN OUTCOME MEASURE

The AEDC measures child development across five domains; Physical Health and Wellbeing, Social Competence, Emotional Maturity, Language and Cognitive Skills (school-based) and Communication Skills and General Knowledge. Children with scores <10th percentile were classified as developmentally vulnerable on, one or more domains (DV1), or two or more domains (DV2).

RESULTS

22.8% and 11.5% of children were classified as DV1 and DV2, respectively. In the adjusted models (relative to the reference category, IPIs of 18-23 months), IPIs of <6 months were associated with an increased risk of children being classified as DV1 (adjusted OR (aOR) 1.17, 95% CI 1.08 to 1.34), DV2 (aOR 1.31, 95% CI 1.10 to 1.54) and an increased risk of developmental vulnerability for the domains of Physical Health and Wellbeing (aOR 1.25, 95% CI 1.06 to 1.48) and Emotional Maturity (aOR 1.36, 95% CI 1.12 to 1.66). All IPIs longer than the reference category were associated with and increased risk of children being classified as DV1 and DV2 (aOR >1.15). IPIs of 60-119 months and ≥120 months, were associated with an increased risk of developmental vulnerability on each of the five AEDC domains, with greater odds for each domain for the longer IPI category.

CONCLUSIONS

IPIs showed independent J-shaped relationships with developmental vulnerability, with short (<6 months) and longer (≥24 months) associated with increased risks of developmental vulnerability.

Short interpregnancy interval and low birth weight births in India: Evidence from National Family Health Survey 2015-16

Evidence on the effect of interpregnancy interval (IPI) on low birth weight (LBW) births is limited in developing countries including India. Our study aims to examine association between IPI and LBW births in India. We used data from the fourth round of the National Family Health Survey (NFHS-4) conducted in 2015–16 with a representative sample of 52,825 most recent births for examining the association between IPI and LBW. IPI is defined as the gap between the first month in which the index pregnancy was reported in the reproductive calendar (referred to as the month of conception) and the month of pregnancy outcome (including live births and terminations) of preceding pregnancy. Reproductive calendar data were used to estimate IPI. Association between IPI and LBW were examined using multivariable binary logistic regressions. Seventeen percent of the births in our sample were LBW, and more than half (57.6%) of these were accompanied with IPI less than 18 months. Prevalence of LBW births was highest among mother's who had IPI less than six months (19.4%). Regression results, adjusted for control variables, indicate that the risk of LBW was significantly higher among births whose mothers had IPI less than six months (odds ratio: 1.19, 95% CI:1.05-1.36) compared with those whose mothers had IPI between 18 and 23 months. This study provides additional evidence on the association between short IPI (<6 months) and LBW births in India. Promoting spacing methods of family planning is an option that India may consider for increasing the IPI and thereby reducing LBW births. Ensuring recommended iron and folic acid tablets/equivalent syrup and TT injections for every pregnant woman may offset the adverse consequences of shorter IPI.

•

12% of the LBW births were accompanied with IPI <6 months, 20% between 6 and 11 months, and 25% between 12 and 17 months.

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The risk of LBW births is higher among mothers having an IPI of <6 months compared with mothers having an IPI of 18–23 months.

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Promoting spacing methods of family planning may consider for increasing the IPI and thereby reducing LBW births in India.

•

Promoting recommended TT injections and iron-folic acid supplements may offset the adverse consequences of short IPI.

The association between interpregnancy interval and severe maternal morbidities using revised national birth certificate data: A probabilistic bias analysis

BACKGROUND

Severe maternal morbidity continues to be on the rise in the US. Short birth spacing is a modifiable risk factor associated with maternal morbidity, yet few studies have examined this association, possibly due to few available data sources to examine these rare events.

OBJECTIVE

To examine the association between interpregnancy interval (IPI) and severe maternal morbidity using near-national birth certificate data and account for known under-reporting using probabilistic bias analysis.

METHODS

We used revised 2014-2017 birth certificate data, restricting to resident women with a non-first-born singleton birth. We examined the following: (a) maternal blood transfusion, (b) admission to intensive care unit (ICU), (c) uterine rupture (among women with a prior caesarean delivery) and (d) third- or fourth-degree perineal laceration (among vaginal deliveries) by IPI categories (<6, 6-11, 12-17, 18-23, 24-59 and 60+ months). Risk ratios and 95% confidence intervals were estimated using log-binomial regression, adjusting for select maternal characteristics. Probabilistic bias analyses were performed.

RESULTS

Compared with IPI 18 to 23 months, adjusted models revealed that the risk of maternal transfusion followed a U-shaped curve with IPI, while risk of ICU admission and perineal laceration increased with longer IPI. Risk of uterine rupture was highest among IPI <6 months. With the exception of maternal transfusion, these findings persisted regardless of the extent or type of misclassification examined in bias analyses.

CONCLUSIONS

Associations between IPI and maternal morbidity varied by outcome, even after adjusting for misclassification of SMM. Differences across maternal health outcomes should be considered when counselling and making recommendations regarding optimal birth spacing.

Interpregnancy interval and risk of perinatal death: a systematic review and meta-analysis

BACKGROUND

Interpregnancy interval (IPI) <6 months is a potentially modifiable risk factor for adverse perinatal health outcomes.

OBJECTIVE

This systematic review evaluated the international literature on the risk of perinatal death associated with IPI.

SEARCH STRATEGY

Two independent reviewers screened titles and abstracts identified in MEDLINE, EMBASE and Scopus from inception to 4 April 2019 (Prospero Registration #CRD42018092792).

SELECTION CRITERIA

Studies were included if they provided a description of IPI measurement and perinatal death, including stillbirth and neonatal death.

DATA COLLECTION AND ANALYSIS

A narrative review was performed for all included studies. Random effects meta-analysis was used to compare unadjusted odds of perinatal death associated with IPI <6 months and IPI ≥6 months. Analyses were performed by outcome of the preceding pregnancy and study location.

MAIN RESULTS

Of the 624 unique articles identified, 26 met the inclusion criteria. The pooled unadjusted odds ratio of perinatal death for IPI <6 months was 1.34 (95% CI 1.17-1.53) following a previous live birth, 0.85 (95% CI 0.73-0.99) following a previous miscarriage and 1.07 (95% CI 0.84-1.36) following a previous stillbirth compared with IPI ≥6 months. However, few high-income country studies reported an association after adjustment. Fewer studies evaluated the impact of long IPI on perinatal death and what evidence was available showed mixed results.

CONCLUSIONS

Results suggest a possible association between short IPI and risk of perinatal death following a live birth, particularly in low- to middle-income countries.

TWEETABLE ABSTRACT

Short IPI <6 months after a live birth was associated with greater risk of perinatal death than IPI ≥6 months.

Influence of Caesarean section-pregnancy interval on uterine rupture risk and IVF pregnancy rates: systematic review and mathematical modelling

RESEARCH QUESTION

What is the influence of the Caesarean section-pregnancy interval (CSPI) on the risk of uterine rupture, and what are the repercussions on IVF pregnancy rates of prolonging it?

STUDY DESIGN

Systematic searches were performed using PubMed MEDLINE to identify studies published up until July 2017 for articles with the following keywords: 'interdelivery interval' and 'uterine rupture'; 'interpregnancy interval' and 'uterine rupture'; 'interpregnancy interval' and 'cesarean section'; and 'uterine rupture' and 'cesarean section'. The search identified 1609 articles, of which six were included (involving 56,419 women). Four reported significantly higher uterine rupture rates in cases of a short CSPI.

RESULTS

From the analysis, the uterine rupture rate can be modelled by a formula corresponding to a hyperbolic curve. There is no clear cut-off in uterine rupture in relation to CSPI. The curve showed a sharp decrease in uterine rupture until the 10th month of CSPI (uterine rupture rate 0.7%), then a moderate and steady decrease until the 40th month (uterine rupture rate 0.4%) and afterwards a very mild decrease. From the data it is possible to calculate, according to the age of the woman, the expected reduction in IVF rates and uterine rupture as CSPI increases.

CONCLUSION

The risk of uterine rupture in relation to CSPI can be represented by means of a hyperbolic curve. After a 10-month CSPI, the expected uterine rupture rate is close to 0.7%. The impact of prolonging or reducing this interval on IVF pregnancy rates can be easily obtained from the table included in the article. This should be helpful in the decision-making process for both patients and physicians.

Short interpregnancy interval as a risk factor for preterm birth in non-Hispanic Black and White women in California

OBJECTIVE

Short interpregnancy interval (IPI) is associated with adverse pregnancy outcomes, including preterm birth (PTB < 37 weeks GA). We investigated whether short IPI (< 6 months) contributes to the higher PTB frequency among non-Hispanic Blacks (NHB).

STUDY DESIGN

Using a linked birth cohort > 1.5 million California live births, we examined frequencies of short IPI between racial/ethnic groups and estimated risks by multivariable logistic regression for spontaneous PTB. We expanded the study to births 1991-2012 and utilized a "within-mother" approach to permit methodologic inquiry about residual confounding.

RESULTS

NHB women had higher frequency (7.6%) of short IPI than non-Hispanic White (NHW) women (4.4%). Adjusted odds ratios for PTB and short IPI were 1.64 (95% CI 1.54, 1.76) for NHW and 1.49 (1.34, 1.65) for NHB. Using within-mother analysis did not produce substantially different results.

CONCLUSIONS

Short IPI is associated with PTB but does not explain risk disparity between NHWs and NHBs.

Association between interpregnancy interval and adverse birth outcomes in women with a previous stillbirth: an international cohort study

BACKGROUND

WHO recommends that women wait at least 2 years after a livebirth and at least 6 months after a miscarriage or induced abortion before conceiving again, to reduce the risk of adverse birth outcomes in the subsequent pregnancy. No recommendation exists for the optimal interval after a stillbirth. We investigated the association between interpregnancy interval after stillbirth and birth outcomes in the subsequent pregnancy.

METHODS

In this international cohort study, we used data from birth records from Finland (1987-2016), Norway (1980-2015), and Western Australia (1980-2015). Consecutive singleton pregnancies in women whose most recent pregnancy had ended in stillbirth of at least 22 weeks' gestation were included in the analysis. Interpregnancy interval was defined as the time between the end of pregnancy (delivery date) and the start of the next pregnancy (delivery date of next pregnancy minus gestational age at birth). We calculated odds ratios (ORs) for stillbirth, preterm birth, and small-for-gestational-age birth by interpregnancy interval by country, adjusted for maternal age, parity, decade of delivery, and gestational length of the previous pregnancy. A fixed-effects meta-analysis was used to estimate pooled ORs.

FINDINGS

We identified 14 452 births in women who had a stillbirth in the previous pregnancy; median interpregnancy interval after stillbirth was 9 months (IQR 4-19). 9109 (63%) women conceived within 12 months of the stillbirth. Of the 14 452 births, 228 (2%) were stillbirths, 2532 (18%) were preterm births, and 1284 (9%) were small-for-gestational-age births. Compared with an interpregnancy interval of 24-59 months, intervals shorter than 12 months were not associated with increased odds of subsequent stillbirth (pooled adjusted OR 1·09 [95% CI 0·63-1·91] for <6 months; 0·90 [0·47-1·71] for 6-11 months), preterm birth (0·91 [0·75-1·11] for <6 months; 0·91 [0·74-1·11] for 6-11 months), or small-for-gestational-age birth (0·66 [0·51-0·85] for <6 months; 0·64 [0·48-0·84] for 6-11 months). Further, we noted no difference in the association between interpregnancy interval and birth outcomes by gestational length of the previous stillbirth.

INTERPRETATION

Conception within 12 months of a stillbirth was common and was not associated with increased risk of adverse outcomes in the subsequent pregnancy. These findings could be used when counselling women who are planning future pregnancies after a stillbirth and for informing future recommendations for pregnancy spacing in a high-income setting.

FUNDING

National Health and Medical Research Council (Australia), and Research Council of Norway.

A Population-Based Matched-Sibling Analysis Estimating the Associations Between First Interpregnancy Interval and Birth Outcomes

The association between a single interpregnancy interval (IPI) and birth outcomes has not yet been explored using matched methods. We modeled the odds of preterm birth, being small for gestational age, and having low birth weight in a second, live-born infant in a cohort of 192,041 sibling pairs born in Western Australia between 1980 and 2010. The association between IPI and birth outcomes was estimated from the interaction between birth order and IPI (with 18-23 months as the reference category), using conditional logistic regression. Matched analysis showed the odds of preterm birth were higher for siblings born following an IPI of <6 months (adjusted interaction odds ratio = 1.22, 95% confidence interval: 1.06, 1.38) compared with those born after an IPI of 18-23 months. There were no significant differences for IPIs of <6 months for other outcomes (small for gestational age or low birth weight). This is the first study to use matched analyses to investigate the association between a single IPI on birth outcomes. IPIs of <6 months were associated with increased odds of preterm birth in second-born infants, although the association is likely smaller than previously estimated by unmatched studies.

Interbirth Interval and Pregnancy Complications and Outcomes: Findings from the Pregnancy Risk Assessment Monitoring System

INTRODUCTION

Although the definition of a short interbirth interval has been inconsistent in the literature, Healthy People 2020 recommends that women wait at least 18 months after a live birth before attempting their next pregnancy. In the United States, approximately 33% of pregnancies are conceived within 18 months of a previous birth. Pregnancies that result from short interbirth intervals can pose serious risks. The objective of this study was to determine the association between interbirth interval and understudied pregnancy complications and outcomes, including small for gestational age (SGA) infants, premature rupture of membranes (PROM), preterm PROM (PPROM), placenta previa, and gestational diabetes, using Pregnancy Risk Assessment and Monitoring System data from Mississippi and Tennessee.

METHODS

This study collected self-reported information from 2212 women on interbirth interval (≤18 months, ie, short; 19-35 months, ie, intermediate; and ≥36 months, ie, long; referent), PPROM, placenta previa, and gestational diabetes. SGA and PROM data were obtained from birth certificates. Logistic regression was used to calculate odds ratios (ORs) and 95% CIs.

RESULTS

After adjustment, there were no strong associations between interbirth interval and PPROM, gestational diabetes, or SGA infants. However, women with shorter intervals had increased odds of PROM (short: OR, 3.54; 95% CI, 1.22-10.23 and intermediate: OR, 4.09; 95% CI, 1.28-13.03) and placenta previa (short: OR, 2.58; 95% CI, 1.10-6.05 and intermediate: OR, 1.69; 95% CI, 0.94-3.05).

DISCUSSION

The study's findings provide further support for encouraging women to space their pregnancies appropriately. Moreover, findings underscore the need to provide women with family planning services so that closely spaced pregnancies and unintended pregnancies can be avoided. Additional studies of the role of interbirth interval on these understudied pregnancy complications and outcomes are warranted.

SMFM Special Report: Putting the "M" back in MFM: Reducing racial and ethnic disparities in maternal morbidity and mortality: A call to action

Racial and ethnic disparities in maternal morbidity and mortality rates are an important public health problem in the United States. Because racial and ethnic minorities are expected to comprise more than one-half of the US population by 2050, this issue needs to be addressed urgently. Research suggests that the drivers of health disparities occur at 3 levels: patient, provider, and system. Although we have recognized this issue and identified elements that contribute to it, knowledge must be converted into action to address it. In addition, despite available funding and databases, research directed towards understanding and reducing these disparities is lacking. This document summarizes findings of a workshop convened at the 2016 Society for Maternal-Fetal Medicine's 36th Annual Pregnancy meeting in Atlanta, GA, to review and make recommendations about immediate actions in clinical care and research that will serve to reduce racial and ethnic disparities in maternal morbidity and mortality rates in the United States.

National Quality Measures in Perinatal Medicine

There are numerous measures of perinatal quality endorsed by national agencies such as the National Quality Forum (NQF). The sheer number of metrics may lead to confusion about what these measures truly assess, and how to interpret variation in these measures across hospitals, health care systems, and geographic regions. This review presents a conceptual model for the numerous validated measures, an overview of the types of measures endorsed for perinatal quality by NQF in 2016, and potential measures absent from endorsement by these national bodies.

Postpartum Health and Wellness: A Call for Quality Woman-Centered Care

Introduction The first 3 months after giving birth can be a challenging time for many women. The Postpartum Health and Wellness special issue explores this period, one that is often overlooked and under-researched. Methods This issue is designed to bring greater focus to the need for woman-centered care during the postpartum period. Articles in this issue focus on four key areas: (1) the postpartum visit and access to care, (2) the content of postpartum care and postpartum health concerns, (3) interconception care including contraception, and (4) policy, systems, and measurement. Results The submissions highlight deficits in the provision of comprehensive care and services during a critical period in women's lives. The research highlighted in this issue supports the recommendation that Maternal and Child Health leaders collaborate to create woman-centered postpartum services that are part of a coordinated system of care. Conclusion In order to achieve optimal health care in the postpartum period it is becoming more apparent that increased flexibility of services, cross-training of providers, a "no wrong door" approach, new insurance and work-place policy strategies, improved communication, and effective coordinated support within a system that values all women and families is required.