To examine the relationship of subfertility with miscarriage, low birth weight, and preterm delivery.
Design
Comparison of time to pregnancy distributions between pregnancies that had different outcomes. Three comparisons were made: (a) miscarriages with live births; within live births, (b) low birth weight infant (up to 2,500 grams) or not low birth weight; (c) preterm birth (37 weeks or less) or not preterm. Cox regression was used to adjust for covariates.
Population
All first pregnancies were analyzed from the National Child Development Study, a large survey of young adults aged 33 years, which is nationally representative of the British-born population.
Main Outcome Measures
The distribution of the time taken to conceive (time to pregnancy), miscarriage, birth weight, and preterm delivery.
Results
Pregnancies that ended in miscarriage tended to take 23% longer to conceive, after adjustment for the other variables. Pregnancies that resulted in preterm delivery tended to take 15% longer to conceive. There was no statistically significant association with low birth weight.
Conclusions
Delay in time to conception is a risk factor for poor obstetric outcome, irrespective of medical intervention.
time to pregnancy subfertility miscarriage risk association, delayed conception preterm delivery poor obstetric outcome, time to pregnancy low birth weight preterm birth, subfertility fecundability pregnancy outcome retrospective cohort, National Child Development Study time to pregnancy UK, conception delay miscarriage risk Cox regression analysis, subfertility as risk factor adverse pregnancy outcomes, fecundity pregnancy loss epidemiology population-based study, time to pregnancy distribution miscarriage live birth comparison, Joffe Li time to pregnancy obstetric outcome
PMID 8005307 8005307 DOI 10.1016/s0015-0282(16)56818-6 10.1016/s0015-0282(16)56818-6 Joffe et al. 1994, Joffe 1994
Cite this article
Joffe, M., & Li, Z. (1994). Association of time to pregnancy and the outcome of pregnancy. Fertility and sterility, 62(1), 71-75. https://doi.org/10.1016/s0015-0282(16)56818-6
Joffe M, Li Z. Association of time to pregnancy and the outcome of pregnancy. Fertil Steril. 1994;62(1):71-75. doi:10.1016/s0015-0282(16)56818-6
Joffe, Michael, and Zhi-Min Li. "Association of time to pregnancy and the outcome of pregnancy." Fertility and sterility, vol. 62, no. 1, 1994, pp. 71-75.
Keywords
Abortion, Spontaneous/epidemiology, Cohort Studies, Female, Humans, Infant, Low Birth Weight, Infant, Newborn, Infertility, Female/physiopathology, Obstetric Labor, Premature/epidemiology, Odds Ratio, Pregnancy, Pregnancy Outcome, Risk Factors, Time Factors, Age Factors, Behavior, Biology, Birth Weight, Body Weight, Demographic Factors, Developed Countries, Economic Factors, Educational Status, Europe, Fertility, Fertility Measurements, Fetal Death, First Pregnancy Intervals, Low Birth Weight, Maternal Age, Mortality, Northern Europe, Parental Age, Physiology, Population, Population Characteristics, Population Dynamics, Pregnancy, Pregnancy Intervals, Pregnancy Outcomes--determinants, Reproduction, Risk Factors, Smoking, Socioeconomic Factors, Socioeconomic Status, Time Factors, United Kingdom
Related articles
Pregnancy Complications · Premature Rupture of Membranes
Hsu JZ et al., 2025·Eur J Obstet Gynecol Reprod Biol·
Endometriosis is a chronic gynaecological condition affecting reproductive-aged women. It has been associated with infertility and potential risks for adverse pregnancy outcomes, although population-level evidence remains limited. This retrospective cohort study, including 147,950 pregnant women aged 20-45 years, used nationwide population-based data to compare the outcomes between women with (n = 11,400) and without (n = 136,550) endometriosis between 2000 and 2021. Baseline characteristics, comorbidities and pregnancy outcomes were compared between the groups. Multivariable regression analyses were performed to calculate adjusted relative risks (aRR) and 95 % confidence intervals (CI) for various pregnancy outcomes, and subgroup analyses were conducted by maternal age and infertility status. Among 147,950 pregnancies, women with endometriosis [mean ± standard deviation (SD) age 32.38 ± 4.51 years] had higher socio-economic status, more comorbidities, and more surgical history compared with women without endometriosis (mean ± SD age 30.06 ± 4.96 years). Women with endometriosis had increased risk of miscarriage (aRR 1.13, 95 % CI 1.03-1.24), preterm birth (aRR 1.31, 95 % CI 1.26-1.37), premature rupture of membranes (aRR 1.11, 95 % CI 1.06-1.16), placenta previa (aRR 1.63, 95 % CI 1.45-1.84), urinary tract infection (aRR 1.44, 95 % CI 1.31-1.59), and caesarean section (aRR 1.13, 95 % CI 1.11-1.16). Subgroup analysis revealed that risk of miscarriage was only higher in women aged 35-45 years and women without infertility. Risks of preterm birth, placenta previa and caesarean section were elevated across all subgroups, suggesting that endometriosis contributes independently to adverse pregnancy outcomes. Endometriosis is an independent risk factor for several pregnancy complications, supporting the need for tailored prenatal care and closer monitoring of affected women to improve maternal outcomes.
Sklar A et al., 2022·American journal of obstetrics and gynecology
After preterm premature rupture of membranes at <24 weeks' gestation, pregnant women may choose continuation (expectant management) or termination of pregnancy, via either dilation and evacuation or labor induction. Neonatal outcomes after expectant management are well described. In contrast, limited research addresses maternal outcomes associated with expectant management compared to termination of pregnancy. This study aimed to compare maternal morbidity after preterm premature rupture of membranes at <24 weeks' gestation in women who choose either expectant management or termination of pregnancy. This retrospective cohort study included women with preterm premature rupture of membranes between 14 0/7 and 23 6/7 weeks' gestation with singleton or twin pregnancies at 3 institutions from 2011 to 2018. We excluded pregnancies complicated by fetal anomalies, rupture of membranes immediately after obstetrical procedures (chorionic villus sampling, amniocentesis, cerclage placement, fetal reduction), spontaneous delivery <24 hours after membrane rupture, and contraindications to expectant management. Our primary outcome was the difference in composite maternal morbidity between women choosing expectant management and women choosing termination of pregnancy. We defined composite maternal morbidity as at least 1 of the following: chorioamnionitis, endometritis, sepsis, unplanned operative procedure after delivery (dilation and curettage, laparoscopy, or laparotomy), injury requiring repair, unplanned hysterectomy, unplanned hysterotomy (excluding cesarean delivery), uterine rupture, hemorrhage of >1000 mL, transfusion, admission to the maternal intensive care unit, acute renal insufficiency, venous thromboembolism, pulmonary embolism, and readmission to the hospital within 6 weeks. We compared the demographic and antenatal characteristics of women choosing expectant management with that of women choosing termination of pregnancy and used logistic regression to quantify the association between initial management decision and composite maternal morbidity. We identified 350 women with pregnancies complicated by preterm premature rupture of membranes at <24 weeks' gestation, and 208 women were eligible for the study. Of the 208 women, 108 (51.9%) chose expectant management as initial management, and 100 (48.1%) chose termination of pregnancy as initial management. Among women selecting termination of pregnancy, 67.0% underwent labor induction, and 33.0% underwent dilation and evacuation. Compared to women who chose termination of pregnancy, women who chose expectant management had 4.1 times the odds of developing chorioamnionitis (38.0% vs 13.0%; 95% confidence interval, 2.03-8.26) and 2.44 times the odds of postpartum hemorrhage (23.1% vs 11.0%; 95% confidence interval, 1.13-5.26). Admissions to the intensive care unit and unplanned hysterectomy only occurred after expectant management (2.8% vs 0.0% and 0.9% vs 0.0%). Of women who chose expectant management, 36.2% delivered via cesarean delivery with 56.4% non-low transverse uterine incisions. Composite maternal morbidity rates were 60.2% in the expectant management group and 33.0% in the termination of pregnancy group. After adjusting for gestational age at rupture, site, race and ethnicity, gestational age at entry to prenatal care, preterm premature rupture of membranes in a previous pregnancy, twin pregnancy, smoking, cerclage, and cervical examination at the time of presentation, expectant management was associated with 3.47 times the odds of composite maternal morbidity (95% confidence interval, 1.52-7.93), corresponding to an adjusted relative risk of 1.91 (95% confidence interval, 1.35-2.73). Among women who chose expectant management, 15.7% avoided morbidity and had a neonate who survived to discharge. Expectant management for preterm premature rupture of membranes at <24 weeks' gestation was associated with a significantly increased risk of maternal morbidity when compared to termination of pregnancy.
Liew Z et al., 2020·Environmental health perspectives
Per- and polyfluoroalkyl substances (PFAS) are widespread persistent organic pollutants and endocrine disruptors. High doses of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) exposure can cause pregnancy loss and infant deaths in animals, but the associations between PFAS exposures and risk of miscarriage in humans are not well studied. Using a case-control study nested within the Danish National Birth Cohort (DNBC, 1996-2002), we compared 220 pregnancies ending in miscarriage during weeks 12-22 of gestation, with 218 pregnancies resulting in live births. Levels of seven types of PFAS [PFOS, PFOA, perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonate (PFHpS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluorooctanesulfonic acid (PFOSA)] were measured in maternal plasma collected in early gestation (mean gestational week 8). We estimated the odds ratios (ORs) and 95% confidence intervals (CIs) for miscarriage and each PFAS as a continuous variable or in quartiles, controlling for maternal age, parity, socio-occupational status, smoking and alcohol intake, gestational week of blood sampling, and maternal history of miscarriage. Stratification by parity and PFAS mixture analyses using weighted quantile sum (WQS) regression were also conducted. We observed a monotonic increase in odds for miscarriage associated with increasing PFOA and PFHpS levels. The ORs comparing the highest PFOA or PFHpS quartile to the lowest were 2.2 (95% CI: 1.2, 3.9) and 1.8 (95% CI: 1.0, 3.2). The ORs were also elevated for the second or third quartile of PFHxS or PFOS, but no consistent exposure-outcome pattern emerged. An interquartile range (IQR) increment in the WQS index of seven PFAS was associated with 64% higher odds for miscarriage (95% CI: 1.15, 2.34). The associations were stronger in parous women, while findings were inconsistent among nulliparous women. Maternal exposures to higher levels of PFOA, PFHpS, and PFAS mixtures were associated with the risk of miscarriage and particularly among parous women. Larger replication studies among nulliparous women are needed to allay concerns about confounding by reproductive history. https://doi.org/10.1289/EHP6202.
Dotters-Katz SK et al., 2017·Obstetrics and gynecology·
Open Access
To identify risk factors for maternal morbidity after previable prelabor rupture of membranes (PROM). We conducted a case-control study of singleton and twin pregnancies complicated by previable PROM (14.0-22.9 weeks of gestation) at a single tertiary care referral institution, 2000-2015. Pregnancies complicated by fetal anomalies, previable PROM within 2 weeks of chorionic villus sampling or amniocentesis, and those with contraindications to expectant management (eg, chorioamnionitis) were excluded. Cases were women with the primary outcome of composite maternal morbidity (defined as having at one or more of the following: sepsis, intensive care unit admission, acute renal insufficiency, uterine curettage, hysterectomy, deep vein thrombosis, pulmonary embolus, blood transfusion, readmission, or maternal death). Controls were women without the primary composite morbidity. Bivariate analysis compared demographic, clinical, and management characteristics of women in the case group and those in the control group. Multivariable logistic regression models were developed to quantify the association between maternal characteristics and composite severe maternal morbidity. During the study period, 174 women presented with by previable PROM and were candidates for expectant management. Sixty-five (37%) women opted for immediate delivery; 109 (63%) elected expectant management. Twenty-five of 174 (14%) experienced one or more components of the composite maternal morbidity (cases) and were compared with 149 (86%) women in the control group. Women in the case group were more not more likely to elect expectant management (68% compared with 59%, P=.40), but were more likely to be aged 35 years or older (40% compared with 14%, P=.002) or to be carrying twins (52% compared with 16%, P<.01). In the regression model, twin gestation and age 35 years or older were both significantly associated with increased odds of composite maternal morbidity (odds ratio [OR] 5.62, 95% confidence interval [CI] 2.21-14.3 and OR 4.00, 95% CI 1.48-10.8, respectively). Antenatal counseling of women with previable PROM should include that one in seven women experience significant morbidity. Although expectant management was not associated with increased risk in this cohort, women with twins or those aged 35 years or older were at substantially increased risk.