Relevance of the miscarriage-new pregnancy interval

Interpregnancy Interval After Pregnancy Loss and Risk of Repeat Miscarriage

OBJECTIVE

To assess whether interpregnancy interval length after a pregnancy loss is associated with risk of repeat miscarriage.

METHODS

This analysis includes pregnant women participating in the Right From the Start (2000-2012) community-based prospective cohort study whose most recent pregnancy before enrollment ended in miscarriage. Interpregnancy interval was defined as the time between a prior miscarriage and the last menstrual period of the study pregnancy. Miscarriage was defined as pregnancy loss before 20 weeks of gestation. Cox proportional hazard models were used to estimate crude and adjusted hazard ratios and 95% CIs for the association between different interpregnancy interval lengths and miscarriage in the study pregnancy. Adjusted models included maternal age, race, parity, body mass index, and education.

RESULTS

Among the 514 study participants who reported miscarriage as their most recent pregnancy outcome, 15.7% had a repeat miscarriage in the study pregnancy (n=81). Median maternal age was 30 years (interquartile range 27-34) and 55.6% of participants had at least one previous livebirth (n=286). When compared with women with interpregnancy intervals of 6-18 months (n=136), women with intervals of less than 3 months (n=124) had the lowest risk of repeat miscarriage (7.3% compared with 22.1%; adjusted hazard ratio 0.33, 95% CI 0.16-0.71). Neither maternal race nor parity modified the association. Attempting to conceive immediately was not associated with increased risk of miscarriage in the next pregnancy.

CONCLUSION

An interpregnancy interval after pregnancy loss of less than 3 months is associated with the lowest risk of subsequent miscarriage. This implies counseling women to delay conception to reduce risk of miscarriage may not be warranted.

Interpregnancy interval following miscarriage and adverse pregnancy outcomes: systematic review and meta-analysis

BACKGROUND

A short interpregnancy interval (IPI) following a delivery is believed to be associated with adverse outcomes in the next pregnancy. The optimum IPI following miscarriage is controversial. Based on a single large-scale study in Latin and South America, the World Health Organization recommends delaying pregnancy for 6 months after a miscarriage to achieve optimal outcomes in the next pregnancy.

OBJECTIVE AND RATIONALE

Our aim was to determine if a short IPI (<6 months) following miscarriage is associated with adverse outcomes in the next pregnancy.

SEARCH METHODS

Studies were retrieved from MEDLINE, Embase and Pubmed, with no time and language restrictions. The search strategy used a combination of Medical Subject Headings terms for miscarriage, IPI and adverse outcomes. Bibliographies of the retrieved articles were also searched by hand. All studies including women with at least one miscarriage, comparing subsequent adverse pregnancy outcomes for IPIs of less than and more than 6 months were included. Two independent reviewers screened titles and abstracts for inclusion. Characteristics of the studies were extracted and quality assessed using Critical Appraisal Skills Programme criteria. A systematic review and meta-analysis were conducted to compare short (<6 months) versus long (>6 months) IPI following miscarriage in terms of risk of further miscarriage, preterm birth, stillbirth, pre-eclampsia and low birthweight babies in the subsequent pregnancy. Review Manager 5.3 was used for conducting meta-analyses.

OUTCOMES

Sixteen studies including 1 043 840 women were included in the systematic review and data from 10 of these were included in one or more meta-analyses (977 972 women). With an IPI of less than 6 months, the overall risk of further miscarriage (Risk ratio (RR) 0.82 95% CI 0.78, 0.86) and preterm delivery (RR 0.79 95% CI 0.75, 0.83) were significantly reduced. The pooled risks of stillbirth (RR 0.88 95% CI 0.76, 1.02); low birthweight (RR 1.05 95% CI 0.48, 2.29) and pre-eclampsia (RR 0.95 95% CI 0.88, 1.02) were not affected by IPI. Similar findings were obtained in subgroup analyses when IPI of <6 months was compared with IPI of 6-12 months and >12 months.

WIDER IMPLICATIONS

This is the first systematic review and meta-analysis providing clear evidence that an IPI of less than 6 months following miscarriage is not associated with adverse outcomes in the next pregnancy. This information may be used to revise current guidance.

Pregnancy loss history at first parity and selected adverse pregnancy outcomes

PURPOSE

To evaluate the association between pregnancy loss history and adverse pregnancy outcomes.

METHODS

Pregnancy history was captured during a computer-assisted personal interview for 21,277 women surveyed in the National Survey of Family Growth (1995-2013). History of pregnancy loss (<20 weeks) at first parity was categorized in three ways: number of losses, maximum gestational age of loss(es), and recency of last pregnancy loss. We estimated risk ratios for a composite measure of selected adverse pregnancy outcomes (preterm, stillbirth, or low birthweight) at first parity and in any future pregnancy, separately, using predicted margins from adjusted logistic regression models.

RESULTS

At first parity, compared with having no loss, having 3+ previous pregnancy losses (adjusted risk ratio (aRR) = 1.66 [95% CI = 1.13, 2.43]), a maximum gestational age of loss(es) at ≥10 weeks (aRR = 1.28 [1.04, 1.56]) or having experienced a loss 24+ months ago (aRR = 1.36 [1.10, 1.68]) were associated with increased risks of adverse pregnancy outcomes. For future pregnancies, only having a history of 3+ previous pregnancy losses at first parity was associated with increased risks (aRR = 1.97 [1.08, 3.60]).

CONCLUSION

Number, gestational age, and recency of pregnancy loss at first parity were associated with adverse pregnancy outcomes in U.S. women.

Adverse pregnancy outcomes among women with prior spontaneous or induced abortions

OBJECTIVE

The aim of the article is to determine whether prior spontaneous abortion (SAB) or induced abortion (IAB), or the interpregnancy interval are associated with subsequent adverse pregnancy outcomes in nulliparous women.

METHODS

We performed a secondary analysis of data collected from nulliparous women enrolled in a completed trial of vitamins C and E or placebo for preeclampsia prevention. Adjusted odds ratios (ORs) for maternal and fetal outcomes were determined for nulliparous women with prior SABs and IABs as compared with primigravid participants.

RESULTS

Compared with primigravidas, women with one prior SAB were at increased risk for perinatal death (adj. OR, 1.5; 95% CI, 1.1-2.3) in subsequent pregnancies. Two or more SABs were associated with an increased risk for spontaneous preterm birth (PTB) (adj. OR, 2.6, 95% CI, 1.7-4.0), preterm premature rupture of membranes (PROM) (adj. OR, 2.9; 95% CI, 1.6-5.3), and perinatal death (adj. OR, 2.8; 95% CI, 1.5-5.3). Women with one previous IAB had higher rates of spontaneous PTB (adj. OR, 1.4; 95% CI, 1.0-1.9) and preterm PROM (OR, 2.0; 95% CI, 1.4-3.0). An interpregnancy interval less than 6 months after SAB was not associated with adverse outcomes.

CONCLUSION

Nulliparous women with a history of SAB or IAB, especially multiple SABs, are at increased risk for adverse pregnancy outcomes.

Successive time to pregnancy among women experiencing pregnancy loss

STUDY QUESTION

Is time to pregnancy (TTP) similar across successive pregnancy attempts among women experiencing pregnancy loss?

SUMMARY ANSWER

TTP after a loss may be longer compared with TTP before a loss.

WHAT IS KNOWN ALREADY

Two pregnancy cohort studies have reported that TTP is similar across pregnancy attempts in fertile women. However, this has not been investigated among women experiencing pregnancy losses.

STUDY DESIGN, SIZE, DURATION

Data for this analysis come from the Longitudinal Investigation of Fertility and the Environment Study, a population-based, preconception cohort of couples attempting pregnancy. During 2005-2009, recruitment was targeted to 16 counties in Michigan and Texas with reported exposures to persistent environmental chemicals. A total of 501 couples were recruited and followed for up to 12 months of pregnancy attempts allowing for continued participation of women with pregnancy losses until censoring.

PARTICIPANTS, SETTING, METHODS

We assessed TTP among 70 couples recruited upon discontinuing contraception for purposes of becoming pregnant and experiencing ≥1 prospectively observed pregnancy losses during 12 months of trying. There were 61 couples who contributed two pregnancy attempts and 9 who contributed three. Women were instructed in the use of urine-based home fertility monitors to time intercourse relative to ovulation and recorded their bleeding patterns in daily journals. TTP was defined as the number of menstrual cycles taken to achieve pregnancy. Women were also instructed in the use of home digital pregnancy tests and asked to begin pregnancy testing on the day of expected menses. Women recorded the results of their pregnancy tests in a daily journal with a single positive pregnancy test result indicating an hCG-confirmed pregnancy. Pregnancy losses were ascertained from a subsequent recorded negative pregnancy test or clinically confirmed loss. We estimated fecundability odds ratios (FORs) comparing subsequent to first TTP using discrete Cox models with robust standard errors, accounting for cycles off contraception before study entry and adjusting for maternal age, body mass index, reproductive history and time-varying cigarette, alcohol and caffeine usage while trying.

MAIN RESULTS AND THE ROLE OF CHANCE

The mean female age was 30.3 ± 4.3 years; 21% had a prior pregnancy loss before study entry. Of the second and third attempts, 59 and 43%, respectively, were longer compared with the first attempt. FORs <1 suggest reduced fecundability or a longer TTP when comparing the second with the first attempt (0.42, 95% confidence interval (CI): 0.28, 0.65), and similarly for the third relative to the first attempt (0.64, 95% CI: 0.18, 2.36). TTP in the second attempt was a median of 1 cycle longer (interquartile range: 0, 3 cycles) compared with TTP in the first attempt.

LIMITATIONS, REASONS FOR CAUTION

As this is the first study to investigate successive TTP exclusively among women experiencing pregnancy loss, our findings await corroboration since most losses occurred early in gestation. As such, the generalizability of our findings for all pregnancy losses awaits further research. We also had limited power to detect a reduction in fecundability for the third compared with first pregnancy attempt.

WIDER IMPLICATIONS OF THE FINDINGS

Unlike fertile women, TTP in women experiencing early pregnancy losses may trend towards longer subsequent attempts. If the findings are corroborated, women experiencing losses may benefit from counselling regarding trying times.

STUDY FUNDING/COMPETING INTERESTS

This research was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (contracts N01-HD-3-3355, N01-HD-3-3356 and NOH-HD-3-3358). K.J.S. was supported by an Intramural Research Training Award from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Division of Intramural Population Health Research. The authors have no conflicts of interest to declare.

Reproductive performance in the next pregnancy for nulliparous women with history of first trimester spontaneous abortion

OBJECTIVE

To determine whether interpregnancy interval after the first spontaneous abortion has an effect on reproductive performance of women in their next pregnancy.

METHOD

A prospective cohort study was conducted on 4,619 women with history of spontaneous abortion in their first pregnancy. Of them 2,422 (52.4 %) conceived within 6 months of the miscarriage (group A) and 2,197 47.6 % after 12 months (group B). The primary outcome was abortion, live birth, termination, or ectopic pregnancy in the next pregnancy. Secondary outcomes were preterm delivery, low birth weight infants, caesarean section rate and occurrence of preeclampsia, placental abruption and induced labour in the second pregnancy.

RESULTS

Women who conceived again within 6 months were less likely to have another abortion, termination, or ectopic pregnancy compared with women with interpregnancy interval more than 12 months. Women with an interpregnancy interval more than 12 months were less likely to have live birth in the second pregnancy and more likely to have a caesarean section, preterm delivery, or infant of low birth weight compared with women who conceived again within 6 months.

CONCLUSIONS

Women who conceive within 6 months after their first spontaneous abortion have better reproductive outcomes and the lowest complication rates in their subsequent pregnancy.

How long after a miscarriage should women wait before becoming pregnant again? Multivariate analysis of cohort data from Matlab, Bangladesh

OBJECTIVE

To determine the optimum interpregnancy interval (IPI) following a miscarriage.

DESIGN

Multivariate analysis of population-based, prospective data from a demographic surveillance system.

SETTING

Pregnancies in Matlab, Bangladesh, between 1977 and 2008.

PARTICIPANTS

9214 women with 10 453 pregnancies that ended in a miscarriage and were followed by another pregnancy outcome.

MAIN OUTCOME MEASURES

Outcome of pregnancy following the miscarriage was singleton live birth, stillbirth, miscarriage or induced abortion. For pregnancies that ended in live birth: early neonatal, late neonatal and postneonatal mortality.

RESULTS

Compared with IPIs of 6-12 months, pregnancies that were conceived ≤3 months after a miscarriage were more likely to result in a live birth and less likely to result in a miscarriage (adjusted relative risk ratio (RRR) 0.70, 95% CI 0.57 to 0.86) or induced abortion (0.50, 0.29 to 0.89). Induced abortions were significantly more likely following IPIs of 18-24 months (2.36, 1.48 to 3.76), 36-48 months (2.73, 1.50 to 4.94), and >48 months (3.32, 1.68 to 2.95), and miscarriages were more likely following IPIs of 12-17 months (1.25, 1.01 to 1.56) and >48 months (1.90, 1.40 to 2.58). No significant effects of IPI duration are seen on the risks of a stillbirth. However, IPIs≤3 months following a miscarriage are associated with significantly higher late neonatal mortality for the infant born at the end of the IPI (adjusted hazard ratio (HR) 1.74, 1.06 to 2.84), and IPIs of 12-18 months are associated with a significantly lower unadjusted risk of postneonatal mortality (0.54, 0.30 to 0.96).

CONCLUSIONS

The shorter the IPI following a miscarriage, the more likely the subsequent pregnancy is to result in a live birth. However, very short IPIs may not be advisable following miscarriages in poor countries like Bangladesh because they are associated with a higher risk of mortality for the infants born after them.

Effect of interpregnancy interval on outcomes of pregnancy after miscarriage: retrospective analysis of hospital episode statistics in Scotland

OBJECTIVE

To determine the optimum interpregnancy interval after miscarriage in a first recorded pregnancy.

DESIGN

Population based retrospective cohort study.

SETTING

Scottish hospitals between 1981 and 2000.

PARTICIPANTS

30,937 women who had a miscarriage in their first recorded pregnancy and subsequently became pregnant.

MAIN OUTCOME MEASURES

The primary end point was miscarriage, live birth, termination, stillbirth, or ectopic pregnancy in the second pregnancy. Secondary outcomes were rates of caesarean section and preterm delivery, low birthweight infants, pre-eclampsia, placenta praevia, placental abruption, and induced labour in the second pregnancy.

RESULTS

Compared with women with an interpregnancy interval of 6-12 months, those who conceived again within six months were less likely to have another miscarriage (adjusted odds ratio 0.66, 95% confidence interval 0.57 to 0.77), termination (0.43, 0.33 to 0.57), or ectopic pregnancy (0.48, 0.34 to 0.69). Women with an interpregnancy interval of more than 24 months were more likely to have an ectopic second pregnancy (1.97, 1.42 to 2.72) or termination (2.40, 1.91 to 3.01). Compared with women with an interpregnancy interval of 6-12 months, women who conceived again within six months and went on to have a live birth in the second pregnancy were less likely to have a caesarean section (0.90, 0.83 to 0.98), preterm delivery (0.89, 0.81 to 0.98), or infant of low birth weight (0.84, 0.71 to 0.89) but were more likely to have an induced labour (1.08, 1.02 to 1.23).

CONCLUSIONS

Women who conceive within six months of an initial miscarriage have the best reproductive outcomes and lowest complication rates in a subsequent pregnancy.

Is there an ideal interpregnancy interval after a live birth, miscarriage or other adverse pregnancy outcomes?

Advice given to women regarding optimum interpregnancy interval (IPI) following spontaneous miscarriage remains controversial. There is robust evidence from many studies including a meta-analysis that after full term or pre-term delivery, IPIs of <18 months and >5 years are associated with increased risk of poor perinatal and maternal outcome. However, there is paucity of good studies to infer the effect of IPI after a spontaneous miscarriage, which is a relatively common event. The results have been variable and inconsistent but a recent good quality study (DaVanzo et al. 2007 ) showed similar pregnancy outcome with IPIs of <6, 6-14, 15-26 and 27-50 months following spontaneous miscarriage. Hence, it seems reasonable to attempt conception soon after an uncomplicated miscarriage in otherwise healthy women depending on their desire. More good quality, preferably prospective studies regarding effect IPI after miscarriage are required for better evidence-based advice.

Does dilation and curettage versus expectant management for spontaneous abortion in patients undergoing in vitro fertilization affect subsequent endometrial development?

In in vitro fertilization patients, treatment of spontaneous abortion with dilation and curettage (D&C) versus expectant management has no long-term effect on subsequent endometrial development, as measured by change in endometrial thickness. A transient reduction in endometrial thickness was found within the first 6 months after D&C, which is a novel finding, but it is likely to have little or no effect on pregnancy rates given the small absolute effect on endometrial thickness.

Effect of the interpregnancy interval after an abortion on maternal and perinatal health in Latin America

OBJECTIVE

To investigate whether the length of the interval between an abortion and the next pregnancy is associated with increased risks of adverse maternal and perinatal outcomes in Latin America.

METHOD

Retrospective cross-sectional study using information from 258,108 women delivering singleton infants and whose previous pregnancy resulted in abortion recorded in the Perinatal Information System database of the Latin American Centre for Perinatology and Human Development, Montevideo, Uruguay, between 1985 and 2002. Adjusted odds ratios were obtained through logistic regression analysis.

RESULT

Compared with the post-abortion interpregnancy intervals of 18 to 23 months, intervals shorter than 6 months were significantly associated with increased risks of maternal anemia, premature rupture of membranes, low birth weight, very low birth weight, preterm delivery, and very preterm delivery.

CONCLUSION

In Latin America, post-abortion interpregnancy intervals shorter than 6 months are independently associated with increased risks of adverse maternal and perinatal outcomes in the next pregnancy.

DEFINITION

Post-abortion interpregnancy interval (PAII): the time elapsed between the day of the abortion and the first day of the last menstrual period for the index pregnancy.

Neonatal outcomes in immediate versus delayed conceptions after spontaneous abortion: a retrospective case series

OBJECTIVE

This study was undertaken to determine differences in neonatal outcomes between successful pregnancies conceived immediately after a spontaneous abortion (SAB) and successful pregnancies conceived after two menstrual cycles or at least 100 days from the spontaneous abortion.

STUDY DESIGN

This study was a retrospective case series. Deliveries were identified from the University of California-San Francisco Perinatal Database among patients with a history of one SAB. Medical records of 268 patients were reviewed. Sixty-four patients fulfilled study criteria, with 19 in the immediate conception group and 45 in the delayed conception group. Categorical variables were analyzed using chi(2) tests and Fisher exact tests for variables with expected values of <5, whereas continuous variables were analyzed using Student t tests.

RESULTS

Neonatal outcomes for the 2 groups were similar, although neonates in the delayed conception group were more likely to have at least one of the following: low birth weight, an Apgar score <7 at 5 minutes, or admission to the neonatal intensive care unit.

CONCLUSION

In this small retrospective case series, there was no evidence of adverse neonatal outcomes associated with conception immediately after a SAB.