Recurrence of Preterm Birth and Early Term Birth

Is mode of first birth a risk factor for subsequent preterm birth?

BACKGROUND

Previous preterm birth is a strong predictor of subsequent preterm birth, but less is known about the causes of preterm birth following a full-term first pregnancy. Recent research has highlighted previous caesarean section as a potential risk factor.

AIM

To examine the relationship between mode of first birth and the risk of subsequent preterm birth in New South Wales (NSW), Australia.

MATERIALS AND METHODS

A population-based record-linkage study of NSW women who had a live singleton first birth at ≥37 weeks gestation, followed by a singleton second birth between 2005 and 2017. Relative risk (RR) and 95% CI of preterm birth in the subsequent pregnancy was calculated using modified Poisson regression, with mode of first birth as the exposure. Spontaneous preterm birth and preterm prelabour caesarean were secondary outcomes.

RESULTS

Women who had either an intrapartum (RR: 1.26, 95% CI 1.19-1.32) or prelabour caesarean (RR: 1.26, 95% CI 1.18-1.35) first birth had a higher risk of subsequent preterm birth (any birth <37 weeks gestation), than those who birthed vaginally. Women who had a previous instrumental birth (RR: 0.85, 95% CI 0.79-0.91) or prelabour caesarean (RR: 0.74, 95% CI 0.67-0.82) had lower risks of subsequent spontaneous preterm birth. However, prior prelabour caesarean also greatly increased risk of subsequent preterm prelabour caesarean (RR: 5.25, 95% CI 4.65-5.93).

CONCLUSIONS

The mode of first birth has differing effects on the risk of subsequent spontaneous preterm birth and preterm prelabour caesarean. Awareness of the risk of subsequent preterm birth following caesarean section may help inform clinical decisions around mode of first birth.

Enabling Factors Associated with Receipt of Interconception Health Care

OBJECTIVES

Preventive health care between pregnancies may benefit future pregnancies and women's long-term health, yet such care is frequently incomplete. We used Andersen's Model of Health Services Use to identify factors associated with receipt of interconception care.

METHODS

This secondary analysis uses data from a trial that recruited women from four health centers in the Baltimore metropolitan area. We used data on factors associated with Andersen's model reported up to 15 months postpartum. Factors included health history (diabetes, hypertension, prematurity), self-rated health, demographics (age, race/ethnicity, education, marital status, employment, income, parity), predisposing factors (depression, stress, social support), and enabling factors (usual place of care, personal doctor or nurse, insurance). Relative risk regression modeled the relationship between these factors and a dependent variable defined as completing both a postpartum visit and one subsequent health care visit. Models also accounted for time since birth, clustering by site, and trial arm.

RESULTS

We included 376 women followed a mean of 272 days postpartum (SD 57), of whom 226 (60%) completed a postpartum and subsequent visit. Women were predominantly non-Hispanic Black (84%) and low income (50% household income < $20,000/year). In regression, two enabling factors were associated with increased receipt of care: having a personal doctor or nurse (RR 1.38, 95% CI 1.11-1.70) and non-Medicaid insurance (RR 1.64, 95% CI 1.09-2.56).

CONCLUSIONS FOR PRACTICE

Enabling factors were associated with receipt of recommended care following birth. These factors may be modifiable components of efforts to improve care during this critical life course period.

Prenatal two-hit stress affects maternal and offspring pregnancy outcomes and uterine gene expression in rats: match or mismatch?

Maternal stress and inflammation excesses can lead to adverse pregnancy outcomes and offspring development. We evaluated whether distinct prenatal stressors affect pregnancy, maternal and offspring outcomes, and uterine gene expression differently when combined than either alone. Long-Evans dams were exposed to psychological or/and (two-hit) immune stress (interleukin-1 beta [IL-1β]), on gestational days 12-18 and 17-delivery, respectively. Gestational length, maternal weight gain, glycaemia and corticosterone levels, offspring weight, and gender effects were recorded. Maternal and offspring uteri were collected at weaning and on postnatal day 160 correspondingly. Uterine expression of genes involved in local progesterone metabolism, neuroendocrine and immune systems were analyzed using quantitative real-time polymerase chain reaction. Maternal two-hit stress increased gestational length variation and the occurrence of adverse pregnancy outcomes while reducing gestational weight gain. Pup weight was negatively affected by prenatal stressors in a gender-specific way. In dams, IL-1β upregulated gene expression of neuroendocrine (Crh, Crhr1) and cytokine genes (Il1b, Il1rn, Il6, and Il10). Conversely, transcriptional patterns in offspring uteri were more variable with gene-specific up- or downregulation by each stressor separately, while exposure to both extensively reduced the expression of neuroendocrine (Hsd11b1), cytokine (Il1a, Il1rn, Il6), and IL-1 receptor genes. In conclusion, maternal stress affects physiological and molecular processes in dams and their offspring; two hits have different effects than single stressors. Outcomes appear generation-, gender-, and stressor-specific. Dampening of offspring uterine gene expression after exposure to multiple stressors could fit within the match/mismatch hypothesis of perinatal programming, with offspring preparing for a stressful life.

Recurrence risk of preterm birth in a subsequent singleton pregnancy after a spontaneous preterm triplet delivery

OBJECTIVE

History of prior preterm birth (PTB) represents one of the strongest risk factors for recurrent PTB. Nevertheless, whether the occurrence of PTB in multifetal gestation is associated with increased risk of PTB in subsequent pregnancies remains unclear. We aimed to determine the recurrence risk of PTB in a subsequent singleton pregnancy after a previous spontaneous preterm triplet delivery.

STUDY DESIGN

A retrospective matched case-control study. The study group comprised all women with spontaneous preterm trichorionic triplet delivery who had a subsequent singleton pregnancy during 2006-2017 at two university hospitals. A control group of women with spontaneous preterm dichorionic twin delivery and a subsequent singleton pregnancy, was established by matching, four-to-one, according to maternal age, parity, gestational age at delivery, and delivery year.

RESULTS

Data from 170 women were analyzed, 34 with preterm triplet delivery and 136 matched control women with preterm twin delivery. Gestational age at the subsequent singleton delivery was higher in those with preterm triplet delivery than in those with preterm twin delivery (median 39 vs 38 weeks, P = 0.02). Women with prior triplet PTB had a significantly lower rate of recurrent PTB as compared with women with prior twin PTB (5.9 % vs. 25.0 %; OR [95 % CI]: 0.19 (0.04, 0.82), P = 0.02) with lower proportions of low-birth weight infants (<2500 g) (0 % vs. 11.8 %, P = 0.04).

CONCLUSIONS

The risk of recurrent PTB following spontaneous PTB in triplet pregnancy was low compared to preterm twin delivery. These data provide reassurance for those who experienced preterm triplet delivery and suggest the need for further studies to understand the mechanisms contributing to PTB in multifetal pregnancies.

Interventions to prevent spontaneous preterm birth in high‐risk women with singleton pregnancy: a systematic review and network meta‐analysis

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To compare the efficacy of current, relevant interventions to prevent preterm birth in women with singleton pregnancy and high individual risk of spontaneous preterm birth. We will consider interventions for women with a history of spontaneous preterm birth or short cervical length and women with asymptomatic vaginal infections.

Associations between unstable housing, obstetric outcomes, and perinatal health care utilization

BACKGROUND

While there is a growing interest in addressing social determinants of health in clinical settings, there are limited data on the relationship between unstable housing and both obstetric outcomes and health care utilization.

OBJECTIVE

The objective of the study was to investigate the relationship between unstable housing, obstetric outcomes, and health care utilization after birth.

STUDY DESIGN

This was a retrospective cohort study. Data were drawn from a database of liveborn neonates linked to their mothers' hospital discharge records (2007-2012) maintained by the California Office of Statewide Health Planning and Development. The analytic sample included singleton pregnancies with both maternal and infant data available, restricted to births between the gestational age of 20 and 44 weeks, who presented at a hospital that documented at least 1 woman as having unstable housing using the International Classification of Diseases, ninth edition, codes (n = 2,898,035). Infants with chromosomal abnormalities and major birth defects were excluded. Women with unstable housing (lack of housing or inadequate housing) were identified using International Classification of Diseases, ninth edition, codes from clinical records. Outcomes of interest included preterm birth (<37 weeks' gestational age), early term birth (37-38 weeks gestational age), preterm labor, preeclampsia, chorioamnionitis, small for gestational age, long birth hospitalization length of stay after delivery (vaginal birth, >2 days; cesarean delivery, >4 days), emergency department visit within 3 months and 1 year after delivery, and readmission within 3 months and 1 year after delivery. We used exact propensity score matching without replacement to select a reference population to compare with the sample of women with unstable housing using a one-to-one ratio, matching for maternal age, race/ethnicity, parity, prior preterm birth, body mass index, tobacco use during pregnancy, drug/alcohol abuse during pregnancy, hypertension, diabetes, mental health condition during pregnancy, adequacy of prenatal care, education, and type of hospital. Odds of an adverse obstetric outcome were estimated using logistic regression.

RESULTS

Of 2794 women with unstable housing identified, 83.0% (n = 2318) had an exact propensity score-matched control. Women with an unstable housing code had higher odds of preterm birth (odds ratio, 1.2, 95% confidence interval, 1.0-1.4, P < .05), preterm labor (odds ratio, 1.4, 95% confidence interval, 1.2-1.6, P < .001), long length of stay (odds ratio, 1.6, 95% confidence interval, 1.4-1.8, P < .001), emergency department visits within 3 months (odds ratio, 2.4, 95% confidence interval, 2.1-2.8, P < .001) and 1 year after birth (odds ratio, 2.7, 95% confidence interval, 2.4-3.0, P < .001), and readmission within 3 months (odds ratio, 2.7, 95% confidence interval, 2.2-3.4, P < .0014) and 1 year after birth (odds ratio, 2.6, 95% confidence interval, 2.2-3.0, P < .001).

CONCLUSION

Unstable housing documentation is associated with adverse obstetric outcomes and high health care utilization. Housing and supplemental income for pregnant women should be explored as a potential intervention to prevent preterm birth and prevent increased health care utilization.

Evaluation of the efficacy of cervical pessary combined with vaginal progesterone in women with a short cervix and additional risk factors for preterm delivery

OBJECTIVE

The aim of this study was to examine the efficacy of a combined management with cervical pessary and vaginal progesterone of women with a singleton pregnancy and a short cervix in both low and high risk-cases based on their previous obstetrical history and maternal factors.

STUDY DESIGN

This was a prospective cohort study of women with a singleton pregnancy and a sonographically detected mid-trimester cervical length ≤ 25 mm. The high-risk group consisted of women with a history of a previous spontaneous preterm birth (PB), or a second-trimester miscarriage, or a loop electrosurgical excision procedure of the cervix (LEEP) while the low-risk group of women without such a history. All women were managed with cervical pessary and daily vaginal administration of 200 mg of progesterone. The primary outcome measure was spontaneous delivery before 34 weeks (238 days) of gestation.

RESULTS

One hundred ninety-six cases with a CL ≤ 25 mm were detected during the study period. Fifty-two women declined to participate in the study. The remaining 144 women were divided into two groups based on the presence (n = 44) or absence (n = 100) of specific risk factors for PB. The rate of PTB < 34 weeks was similar in both low and high-risk pregnancies while a significantly higher rate of sPTB < 37 weeks was found in women with high-risk pregnancies (p = .005).

CONCLUSION

The combined treatment of cervical pessary and vaginal progesterone has a similar influence on preterm delivery rate < 34 weeks, in both low and high-risk women, with a mid-trimester short cervix.

Previous Adverse Outcome of Term Pregnancy and Risk of Preterm Birth in Subsequent Pregnancy

Objective Evaluate risk of preterm birth (PTB, < 37 completed weeks' gestation) among a population of women in their second pregnancy with previous full term birth but other adverse pregnancy outcome. Methods The sample included singleton live born infants between 2007 and 2012 in a birth cohort file maintained by the California Office of Statewide Health Planning and Development. The sample was restricted to women with two pregnancies resulting in live born infants and first birth between 39 and 42 weeks' gestation. Logistic regression was used to calculate the risk of PTB in the second birth for women with previous adverse pregnancy outcome including: small for gestational age (SGA) infant, preeclampsia, placental abruption, or neonatal death (≤ 28 days). Risks were adjusted for maternal factors recorded for second birth. Results The sample included 133,622 women. Of the women with any previous adverse outcome, 4.7% had a PTB while just 3.0% of the women without a previous adverse outcome delivered early (relative risk adjusted for maternal factors known at delivery 1.4, 95% CI 1.3-1.5). History of an SGA infant, placental abruption, or neonatal death increased the adjusted risk of PTB in their second birth by 1.5-3.7-fold. History of preeclampsia did not elevate the risk of a preterm birth in the subsequent birth. Conclusions for Practice The findings indicate that women with previous SGA infant, placental abruption, or neonatal death, despite a term delivery, may be at increased risk of PTB in the subsequent birth. These women may be appropriate participates for future interventions aimed at reduction in PTB.

At the forefront of psychoneuroimmunology in pregnancy: Implications for racial disparities in birth outcomes PART 1: Behavioral risks factors

Birth prior to full term is a substantial public health issue. In the US, ˜400,000 babies per year are born preterm (<37 weeks), while>1 million are early term (37-38^6/7 weeks). Birth prior to full term confers risk both immediate and long term, including neonatal intensive care, decrements in school performance, and increased mortality risk from infancy through young adulthood. Risk for low birth weight and preterm birth are 1.5-2 times greater among African Americans versus Whites. Psychosocial stress related to being a member of a discriminated racial minority group contributes substantially to these racial disparities. Providing promising targets for intervention, depressed mood, anxiety, and poor sleep are each linked with exposure to chronic stress, including racial discrimination. A rigorous transdisciplinary approach addressing these gaps holds great promise for clinical impact in addressing racial disparities as well as ameliorating effects of stress on perinatal health more broadly. As will be reviewed in a companion paper, the mechanistic roles of physiological sequelae to stress - including neuroendocrine, inflammatory regulation, biological aging, and the microbiome - also require delineation.

Development and validation of a clinical model for preconception and early pregnancy risk prediction of gestational diabetes mellitus in nulliparous women

Implementation of dietary and lifestyle interventions prior to and early in pregnancy in high risk women has been shown to reduce the risk of gestational diabetes mellitus (GDM) development later in pregnancy. Although numerous risk factors for GDM have been identified, the ability to accurately identify women before or early in pregnancy who could benefit most from these interventions remains limited. As nulliparous women are an under-screened population with risk profiles that differ from their multiparous counterparts, development of a prediction model tailored to nulliparous women may facilitate timely preventive intervention and improve maternal and infant outcomes. We aimed to develop and validate a model for preconception and early pregnancy prediction of gestational diabetes mellitus based on clinical risk factors for nulliparous women. A risk prediction model was built within a large California birth cohort including singleton live birth records from 2007-2012. Model accuracy was assessed both internally and externally, within a cohort of women who delivered at University of Iowa Hospitals and Clinics between 2009-2017, using discrimination and calibration. Differences in predictive accuracy of the model were assessed within specific racial/ethnic groups. The prediction model included five risk factors: race/ethnicity, age at delivery, pre-pregnancy body mass index, family history of diabetes, and pre-existing hypertension. The area under the curve (AUC) for the California internal validation cohort was 0.732 (95% confidence interval (CI) 0.728, 0.735), and 0.710 (95% CI 0.672, 0.749) for the Iowa external validation cohort. The model performed particularly well in Hispanic (AUC 0.739) and Black women (AUC 0.719). Our findings suggest that estimation of a woman's risk for GDM through model-based incorporation of risk factors accurately identifies those at high risk (i.e., predicted risk >6%) who could benefit from preventive intervention encouraging prompt incorporation of this tool into preconception and prenatal care.

Risk of singleton preterm birth after prior twin preterm birth: a cohort study

Objective: To determine whether preterm birth in a twin pregnancy increases the risk of subsequent preterm birth (PTB) in a singleton pregnancy and to identify predictors for singleton PTB in women with previous twin PTB.Method: A retrospective cohort study of women with prior twin birth followed by a singleton birth in two tertiary referral centres between 2000 and 2016 was conducted. Rate of PTB in subsequent singleton pregnancy was compared between women who experienced previous preterm versus term twin birth. Analysis was further stratified by gestational age at twin and singleton birth, etiology for PTB and chorionicity in the twin pregnancy.Results: A total of 378 women met the inclusion criteria, of whom 252 (66.7%) experienced PTB in the index twin pregnancy. The overall rate of PTB in the subsequent singleton pregnancy was 11.6% (44/378). Women with prior twin PTB had a higher rate of PTB in the subsequent singleton pregnancy compared with women with prior term twin birth (17.5 versus 6.3%, p = .003, or 3.12, 95%-CI 1.42-6.85), mainly due to a higher rate of late singleton preterm birth (13.1 versus 4.0%, p = .005). Findings of higher odds of PTB in the subsequent singleton pregnancy was limited to women who gave birth before 34^0/7 weeks in the twin pregnancy and was related to the degree of prematurity (prior twin PTB at 30^0/7-33^6/7weeks: OR 3.09, 95%-CI 1.12-8.51; prior twin PTB at <30^0/7weeks: OR 5.8, 95%-CI 2.46-13.68). The association between previous twin PTB and subsequent singleton PTB was limited to women with prior spontaneous twin PTB (OR 3.34, 95%-CI 1.50-7.45).Conclusion: Women with a history of spontaneous PTB in a twin pregnancy are at increased odds of PTB in subsequent singleton pregnancies compared to women with prior term twin birth, and the risk is related to the severity of prematurity in the index twin pregnancy.

Prediction of preterm birth with and without preeclampsia using mid-pregnancy immune and growth-related molecular factors and maternal characteristics

OBJECTIVE

To evaluate if mid-pregnancy immune and growth-related molecular factors predict preterm birth (PTB) with and without (±) preeclampsia.

STUDY DESIGN

Included were 400 women with singleton deliveries in California in 2009-2010 (200 PTB and 200 term) divided into training and testing samples at a 2:1 ratio. Sixty-three markers were tested in 15-20 serum samples using multiplex technology. Linear discriminate analysis was used to create a discriminate function. Model performance was assessed using area under the receiver operating characteristic curve (AUC).

RESULTS

Twenty-five serum biomarkers along with maternal age <34 years and poverty status identified >80% of women with PTB ± preeclampsia with best performance in women with preterm preeclampsia (AUC = 0.889, 95% confidence interval (0.822-0.959) training; 0.883 (0.804-0.963) testing).

CONCLUSION

Together with maternal age and poverty status, mid-pregnancy immune and growth factors reliably identified most women who went on to have a PTB ± preeclampsia.

Factors associated with short interpregnancy interval among women treated with in vitro fertilization

PURPOSE

To evaluate factors associated with interpregnancy interval (IPI) among women treated with in vitro fertilization (IVF).

METHODS

Women with at least two cycles of IVF between 2004 and 2013 were identified from the SART CORS database and grouped by age at first cycle, infertility diagnosis, IVF treatment parameters, and cycle 1 outcome (singleton or multiple live birth or no live birth, length of gestation, and birthweight). The distributions of IPIs (in months, 0-5, 6-11, 12-17, 18-23, and ≥ 24) were compared across these factors. IPI was fit as a function of these factors by a general linear model, separately for singleton and multiple live births and no live births at cycle 1.

RESULTS

The study included 93,546 women with two consecutive IVF cycles where the first cycle resulted in a clinical intrauterine pregnancy or a live birth. Among women with a live birth in cycle 1, there was a general pattern of longer IPI for younger women compared to older women. Women with a multiple birth waited longer before initiating a second cycle than women with a singleton birth. For women with no live birth in the first cycle, nearly three fourths initiated cycle 2 within 6 months, regardless of their age. Short (0-5 months) IPI was associated with preterm delivery, older maternal age, and use of donor oocytes.

CONCLUSIONS

Age of the mother, outcome of the first pregnancy, and treatment factors affect the length of the interpregnancy interval. Because short IPI has been associated with poor outcomes, women who are at risk for short IPI should be counseled about these outcome risks.

Vaginal progesterone is as effective as cervical cerclage to prevent preterm birth in women with a singleton gestation, previous spontaneous preterm birth, and a short cervix: updated indirect comparison meta-analysis

BACKGROUND

An indirect comparison meta-analysis published in 2013 reported that both vaginal progesterone and cerclage are equally efficacious for preventing preterm birth and adverse perinatal outcomes in women with a singleton gestation, previous spontaneous preterm birth, and a sonographic short cervix. The efficacy of vaginal progesterone has been challenged after publication of the OPPTIMUM study. However, this has been resolved by an individual patient-data meta-analysis (Am J Obstet Gynecol. 2018;218:161-180).

OBJECTIVE

To compare the efficacy of vaginal progesterone and cerclage in preventing preterm birth and adverse perinatal outcomes in women with a singleton gestation, previous spontaneous preterm birth, and a midtrimester sonographic short cervix.

DATA SOURCES

MEDLINE, EMBASE, LILACS, and CINAHL (from their inception to March 2018); Cochrane databases, bibliographies, and conference proceedings.

STUDY ELIGIBILITY CRITERIA

Randomized controlled trials comparing vaginal progesterone to placebo/no treatment or cerclage to no cerclage in women with a singleton gestation, previous spontaneous preterm birth, and a sonographic cervical length <25 mm.

STUDY APPRAISAL AND SYNTHESIS METHODS

Updated systematic review and adjusted indirect comparison meta-analysis of vaginal progesterone vs cerclage using placebo/no cerclage as the common comparator. The primary outcomes were preterm birth <35 weeks of gestation and perinatal mortality. Pooled relative risks (RRs) with 95% confidence intervals were calculated.

RESULTS

Five trials comparing vaginal progesterone vs placebo (265 women) and 5 comparing cerclage vs no cerclage (504 women) were included. Vaginal progesterone, compared to placebo, significantly reduced the risk of preterm birth <35 and <32 weeks of gestation, composite perinatal morbidity/mortality, neonatal sepsis, composite neonatal morbidity, and admission to the neonatal intensive care unit (RRs from 0.29 to 0.68). Cerclage, compared to no cerclage, significantly decreased the risk of preterm birth <37, <35, <32, and <28 weeks of gestation, composite perinatal morbidity/mortality, and birthweight <1500 g (RRs from 0.64 to 0.70). Adjusted indirect comparison meta-analyses did not show statistically significant differences between vaginal progesterone and cerclage in the reduction of preterm birth or adverse perinatal outcomes.

CONCLUSION

Vaginal progesterone and cerclage are equally effective for preventing preterm birth and improving perinatal outcomes in women with a singleton gestation, previous spontaneous preterm birth, and a midtrimester sonographic short cervix. The choice of treatment will depend on adverse events and cost-effectiveness of interventions and patient/physician's preferences.

Disparities in Postpartum Contraceptive Counseling and Provision Among Mothers of Preterm Infants

OBJECTIVE

Use of effective contraception could be one method to decrease recurrent preterm birth by increasing intervals between pregnancies. We assessed correlates of contraceptive counseling and uptake among women who delivered preterm.

MATERIALS AND METHODS

This is a retrospective cohort study of women who delivered live-born singletons or twins before 32 weeks' gestation. We assessed documented contraceptive counseling and method uptake by postpartum discharge, using inpatient medical records, and correlates of highly effective contraception uptake by the postpartum visit using outpatient records.

RESULTS

Of 594 eligible women, 44.6% (n = 265) had documented inpatient contraceptive counseling, but only 21.4% (n = 127) left the hospital using a World Health Organization (WHO) tier 1 or 2 method. Women who were younger, non-Hispanic black, multiparous, and delivered at earlier gestational ages were more likely to have inpatient counseling documented. Compared with women with private insurance, women with public insurance were more likely to have documented counseling (22.8% vs. 87.5%, p < 0.001; adjusted odds ratio [aOR] 9.55, 95% confidence interval [CI] 5.31-17.2) and to uptake a WHO tier 1 or 2 method as an inpatient (5.8% vs. 52.0%, p < 0.001; aOR 9.51, 95% CI 4.78-18.9). Of the 175 women with outpatient records available who attended a postpartum visit, only 54.9% (n = 96) adopted a WHO tier 1 or tier 2 method.

CONCLUSION

Although all women in this cohort were at risk of recurrent preterm birth, counseling about contraception after a preterm birth (<32 weeks) was not universal. Women with multiple risk factors for recurrent preterm birth, such as multiparity and public insurance, were more likely to have received documented contraceptive counseling and highly effective contraceptives.

Are risk factors for preterm and early-term live singleton birth the same? A population-based study in France

OBJECTIVES

To investigate whether risk factors for preterm (<37 weeks gestation) and early-term birth (37 and 38 weeks gestation) are similar.

DESIGN

Nationally representative cross-sectional study of births.

SETTING

France in 2010.

PARTICIPANTS

Live singleton births (n=14 326).

PRIMARY AND SECONDARY OUTCOME MEASURES

Preterm and early-term birth rates overall and by mode of delivery (spontaneous and indicated). Risk factors were maternal sociodemographic characteristics, previous preterm birth, height, prepregnancy body mass index (BMI) and smoking, assessed using multinomial regression models with full-term births 39 weeks and over as the reference group.

RESULTS

There were 5.5% preterm and 22.5% early-term births. Common risk factors were: a previous preterm delivery (adjusted relative risk ratio (aRRR) 8.2 (95% CI 6.2 to 10.7) and aRRR 2.4 (95% CI 2.0 to 3.0), respectively), short stature, underweight (overall and in spontaneous deliveries), obesity (in indicated deliveries only), a low educational level and Sub-Saharan African origin. In contrast, primiparity was a risk factor only for preterm birth, aRRR 1.8 (95% CI 1.5 to 2.2), while higher parity was associated with greater risk of early-term birth.

CONCLUSIONS

Most population-level risk factors were common to both preterm and early-term birth with the exception of primiparity, and BMI which differed by mode of onset of delivery. Our results suggest that preterm and early-term birth share similar aetiologies and thus potentially common strategies for prevention.

Sleep Disorder Diagnosis During Pregnancy and Risk of Preterm Birth

OBJECTIVE

To test the hypothesis that sleep disorder diagnosis would be associated with increased risk of preterm birth and to examine risk by gestational age, preterm birth type, and specific sleep disorder (insomnia, sleep apnea, movement disorder, and other).

METHODS

In this observational study, participants were from a cohort of nearly 3 million women in California between 2007 and 2012. Inclusion criteria were women with singleton neonates liveborn between 20 and 44 weeks of gestation without chromosomal abnormalities or major structural birth defects linked to a hospital discharge database maintained by the California Office of Statewide Health Planning and Development and without mental illness during pregnancy. Sleep disorder was defined based on International Classification of Diseases, 9th Revision, Clinical Modification diagnostic code (n=2,265). Propensity score matching was used to select a referent population at a one-to-one ratio. Odds of preterm birth were examined by gestational age (less than 34 weeks, 34-36 weeks, and less than 37 weeks of gestation) and type (spontaneous, indicated).

RESULTS

Prevalence of preterm birth (before 37 weeks of gestation) was 10.9% in the referent group compared with 14.6% among women with a recorded sleep disorder diagnosis. Compared with the referent group, odds (95% CI, P value, percentage) of preterm birth were 1.3 (1.0-1.7, P=.023, 14.1%) for insomnia and 1.5 (1.2-1.8, P<.001, 15.5%) for sleep apnea. Risk varied by gestational age and preterm birth type. Odds of preterm birth were not significantly increased for sleep-related movement disorders or other sleep disorders.

CONCLUSION

Insomnia and sleep apnea were associated with significantly increased risk of preterm birth. Considering the high prevalence of sleep disorders during pregnancy and availability of evidence-based nonpharmacologic interventions, current findings suggest that screening for severe presentations would be prudent.

Vaginal progesterone pessaries for pregnant women with a previous preterm birth to prevent neonatal respiratory distress syndrome (the PROGRESS Study): A multicentre, randomised, placebo-controlled trial

BACKGROUND

Neonatal respiratory distress syndrome, as a consequence of preterm birth, is a major cause of early mortality and morbidity. The withdrawal of progesterone, either actual or functional, is thought to be an antecedent to the onset of labour. There remains limited information on clinically relevant health outcomes as to whether vaginal progesterone may be of benefit for pregnant women with a history of a previous preterm birth, who are at high risk of a recurrence. Our primary aim was to assess whether the use of vaginal progesterone pessaries in women with a history of previous spontaneous preterm birth reduced the risk and severity of respiratory distress syndrome in their infants, with secondary aims of examining the effects on other neonatal morbidities and maternal health and assessing the adverse effects of treatment.

METHODS

Women with a live singleton or twin pregnancy between 18 to <24 weeks' gestation and a history of prior preterm birth at less than 37 weeks' gestation in the preceding pregnancy, where labour occurred spontaneously or in association with cervical incompetence or following preterm prelabour rupture of the membranes, were eligible. Women were recruited from 39 Australian, New Zealand, and Canadian maternity hospitals and assigned by randomisation to vaginal progesterone pessaries (equivalent to 100 mg vaginal progesterone) (n = 398) or placebo (n = 389). Participants and investigators were masked to the treatment allocation. The primary outcome was respiratory distress syndrome and severity. Secondary outcomes were other respiratory morbidities; other adverse neonatal outcomes; adverse outcomes for the woman, especially related to preterm birth; and side effects of progesterone treatment. Data were analysed for all the 787 women (100%) randomised and their 799 infants.

FINDINGS

Most women used their allocated study treatment (740 women, 94.0%), with median use similar for both study groups (51.0 days, interquartile range [IQR] 28.0-69.0, in the progesterone group versus 52.0 days, IQR 27.0-76.0, in the placebo group). The incidence of respiratory distress syndrome was similar in both study groups-10.5% (42/402) in the progesterone group and 10.6% (41/388) in the placebo group (adjusted relative risk [RR] 0.98, 95% confidence interval [CI] 0.64-1.49, p = 0.912)-as was the severity of any neonatal respiratory disease (adjusted treatment effect 1.02, 95% CI 0.69-1.53, p = 0.905). No differences were seen between study groups for other respiratory morbidities and adverse infant outcomes, including serious infant composite outcome (155/406 [38.2%] in the progesterone group and 152/393 [38.7%] in the placebo group, adjusted RR 0.98, 95% CI 0.82-1.17, p = 0.798). The proportion of infants born before 37 weeks' gestation was similar in both study groups (148/406 [36.5%] in the progesterone group and 146/393 [37.2%] in the placebo group, adjusted RR 0.97, 95% CI 0.81-1.17, p = 0.765). A similar proportion of women in both study groups had maternal morbidities, especially those related to preterm birth, or experienced side effects of treatment. In 9.9% (39/394) of the women in the progesterone group and 7.3% (28/382) of the women in the placebo group, treatment was stopped because of side effects (adjusted RR 1.35, 95% CI 0.85-2.15, p = 0.204). The main limitation of the study was that almost 9% of the women did not start the medication or forgot to use it 3 or more times a week.

CONCLUSIONS

Our results do not support the use of vaginal progesterone pessaries in women with a history of a previous spontaneous preterm birth to reduce the risk of neonatal respiratory distress syndrome or other neonatal and maternal morbidities related to preterm birth. Individual participant data meta-analysis of the relevant trials may identify specific women for whom vaginal progesterone might be of benefit.

TRIAL REGISTRATION

Current Clinical Trials ISRCTN20269066.

Maternal serum lead level during pregnancy is positively correlated with risk of preterm birth in a Chinese population

Lead (Pb) is a well-known developmental toxicant. The aim of the present study was to analyze the association between maternal serum Pb level and risk of preterm birth in a population-based birth cohort study. The present study analyzed a sub-study of the China-Anhui Birth Cohort that recruited 3125 eligible mother-and-singleton-offspring pairs. Maternal serum Pb level was measured by graphite furnace atomic absorption spectrometry. All subjects were classified into three groups by tertile division according to serum Pb level: Low-Pb (L-Pb, <1.18 μg/dl), Medium-Pb (M-Pb, 1.18-1.70 μg/dl), and High-Pb (H-Pb, ≥1.71 μg/dl). The rate of preterm birth was 2.8% among subjects with L-Pb, 6.1% among subjects with M-Pb, and 8.1% among subjects with H-Pb, respectively. After controlling confounding factors, the adjusted OR for preterm birth was 2.33 (95%CI: 1.49, 3.65) among subjects with M-Pb and 3.09 (95%CI: 2.01, 4.76) among subjects with H-Pb. Of interest, maternal Pb exposure in early gestational stage than in middle gestational stage was more susceptible to preterm birth. Moreover, maternal serum Pb level was only associated with increased risk of late preterm birth. The present study provides evidence that maternal serum Pb level during pregnancy is positively associated with risk of preterm birth in a Chinese population.

Risk of recurrent spontaneous preterm birth: a systematic review and meta-analysis

OBJECTIVE

To determine the risk of recurrent spontaneous preterm birth (sPTB) following sPTB in singleton pregnancies.

DESIGN

Systematic review and meta-analysis using random effects models.

DATA SOURCES

An electronic literature search was conducted in OVID Medline (1948-2017), Embase (1980-2017) and ClinicalTrials.gov (completed studies effective 2017), supplemented by hand-searching bibliographies of included studies, to find all studies with original data concerning recurrent sPTB.

STUDY ELIGIBILITY CRITERIA

Studies had to include women with at least one spontaneous preterm singleton live birth (<37 weeks) and at least one subsequent pregnancy resulting in a singleton live birth. The Newcastle-Ottawa Scale was used to assess study quality.

RESULTS

Overall, 32 articles involving 55 197 women, met all inclusion criteria. Generally studies were well conducted and had a low risk of bias. The absolute risk of recurrent sPTB at <37 weeks' gestation was 30% (95% CI 27% to 34%). The risk of recurrence due to preterm premature rupture of membranes (PPROM) at <37 weeks gestation was 7% (95% CI 6% to 9%), while the risk of recurrence due to preterm labour (PTL) at <37 weeks gestation was 23% (95% CI 13% to 33%).

CONCLUSIONS

The risk of recurrent sPTB is high and is influenced by the underlying clinical pathway leading to the birth. This information is important for clinicians when discussing the recurrence risk of sPTB with their patients.