Obstetric consequences of subfertility: a retrospective cohort study

Measuring non-events: infertility estimation using cross-sectional, population-based data from four countries in sub-Saharan Africa

STUDY QUESTION

Does the prevalence of 12-month infertility in Burkina Faso, Côte d'Ivoire, Kenya, and Uganda differ between women trying to conceive and the broader population of women exposed to unprotected sex, and how are prevalence estimates affected by model assumptions and adjustments?

SUMMARY ANSWER

Estimates of 12-month infertility among tryers ranged from 8% in Burkina Faso to 30% in Côte d'Ivoire, increasing substantially among a larger population of women exposed to unprotected intercourse.

WHAT IS KNOWN ALREADY

While having a child is a fundamental human experience, the extent to which women and couples experience infertility is a neglected area of research, particularly in sub-Saharan Africa. Existing estimates of infertility in this region vary widely from 2% to 32%, however, potential impacts of variability in study populations and model assumptions have not been well-examined.

STUDY DESIGN, SIZE, DURATION

We used cross-sectional nationally representative survey data from Burkina Faso, Côte d'Ivoire, Kenya, and Uganda. We employed a multi-stage cluster random sampling design with probability proportional to the size selection of clusters within each country to produce representative samples of women aged 15-49. Samples ranged from 3864 in Côte d'Ivoire to 9489 in Kenya.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We created two analytic samples in each country-tryers and a broader sample of women exposed to unprotected sex-exploring differences in population characteristics and estimating the period prevalence of 12-month infertility using the current duration (CD) approach. We also examined the impact of several model assumptions within each of the two analytic samples, including adjustments for recent injectable contraceptive use, unrecognized pregnancy, infertility treatment, underreported contraceptive use, and sexual activity.

MAIN RESULTS AND THE ROLE OF CHANCE

Employing the CD approach among tryers produced an overall 12-month infertility prevalence of 7.9% (95% CI 6.6-12.7) in Burkina Faso, 29.6% (95% CI 15.3-100.0) in Côte d'Ivoire, 24.5% (95% CI 16.5-34.6) in Kenya, and 14.7% (95% CI 8.1-22.4) in Uganda. Results among women exposed to unprotected intercourse indicated much higher levels of infertility, ranging from 22.4% (95% CI 18.6-30.8) in Uganda to 63.7% (95% CI 48.8-87.9) in Côte d'Ivoire. Sensitivity analyses suggest infertility estimates are particularly sensitive to adjustments around pregnancy recognition timing and sexual activity, with little impact of adjustments for recent injectable contraceptive use, infertility treatment, and underreporting of traditional and coital dependent contraceptive use.

LIMITATIONS, REASONS FOR CAUTION

There was substantial digit preference in responses at 12 months, particularly among the tryers, which could introduce bias. Data quality concerns in the reproductive calendar may impact the accuracy of the CD approach among the broader sample of women exposed to unprotected sex, particularly with regard to underreported contraceptive use, induced and spontaneous abortions, and unrecognized pregnancies. Lastly, we lacked information on postpartum amenorrhea or abstinence.

WIDER IMPLICATIONS OF THE FINDINGS

Understanding the inconsistencies in definition and analytic approach and their implications for infertility estimation is important for reliably monitoring population-level infertility trends, identifying factors influencing infertility, improving prevention programs, and ensuring access to quality treatment and services.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by grants from the Bill & Melinda Gates Foundation (INV009639) and the National Institute of Child Health and Human Development (K01HD107172). The funders were not involved in the study design, analyses, manuscript writing, or the decision to publish. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

The relationship between cesarean delivery and fecundability: a population-based cohort study

BACKGROUND

Previous studies have found that women who undergo cesarean delivery have fewer pregnancies. Cesarean delivery is also more common among women with lower fecundability. The potential role of cesarean delivery in reduced fecundability is not known.

OBJECTIVE

This study aimed to assess the bidirectional relationship between cesarean delivery and fecundability.

STUDY DESIGN

This was a prospective cohort study based on data from the Norwegian Mother, Father, and Child Cohort study linked with the Medical Birth Registry of Norway. We estimated the fecundability ratio (per cycle probability of pregnancy) and relative risk of infertility (time to pregnancy ≥12 months) by mode of delivery in the previous delivery among 42,379 women. For the reverse association, we estimated the relative risk of having a cesarean delivery by fecundability (the number of cycles women needed to conceive) among 74,024 women.

RESULTS

The proportion of women with infertility was 7.3% (2707/37,226) among women with a previous vaginal delivery and 9.9% (508/5153) among women with a previous cesarean delivery, yielding an adjusted relative risk of 1.21 (95% confidence interval, 1.10-1.33). Women with a previous cesarean delivery also had a lower fecundability ratio (0.90; 95% confidence interval, 0.88-0.93) than women with a previous vaginal delivery. When assessing the reverse association between fecundability and cesarean delivery, we found that women who did not conceive within 12 or more cycles had a higher risk for cesarean delivery (adjusted relative risk, 1.57; 95% confidence interval, 1.48-1.66) than women who conceived within the first 2 cycles. The associations remained after controlling for sociodemographic and clinical risk factors and were observed across parity groups.

CONCLUSION

Among women with more than 1 child, those who had a previous cesarean delivery subsequently had a lower fecundability ratio and an increased infertility risk than those who had a vaginal delivery. However, women who needed a longer time to conceive were also more prone to be delivered by cesarean delivery, indicating a bidirectional relationship between cesarean delivery and fecundability. This could suggest a common underlying explanatory mechanism and that the surgical procedure itself may not or only partly directly influence fecundability.

Polygenic embryo screening: are there potential maternal and fetal harms?

Polygenic embryo screening (PES) and its derivate the Embryo Health Score (EHS) have generated interest in both infertile and fertile populations due to their potential ability to select embryos with a reduced risk of disease and improved long-term health outcomes. Concerns have been raised regarding the potential harms of IVF itself, including possible epigenetic changes that may affect the health of the offspring in late adulthood, which are not fully captured in the EHS calculation. Knowledge of the potential impacts of the trophectoderm biopsy, which is a key component of the PES procedure, on the offsprings' health is limited by the heterogeneity of the population characteristics used in the published studies. Nonetheless, the literature suggests a possible increased risk of preterm delivery, birth defects and pre-eclampsia after trophectoderm biopsy. Overall, the risks of PES for prenatal and postnatal health remain uncertain, and further research is needed. Counselling patients regarding these risks before considering PES is important, to provide an understanding of the risks and benefits. This review aims to highlight some of these issues, the need for continued investigation in this area, and the importance of informed decision-making in the context of PES.

Risk of Hypertensive Disorders in Pregnancy After Fresh and Frozen Embryo Transfer in Assisted Reproduction: A Population-Based Cohort Study With Within-Sibship Analysis

BACKGROUND

Frozen embryo transfer (frozen-ET) is increasingly common because of improved cryopreservation methods and elective freezing of all embryos. Frozen-ET is associated with higher risk of hypertensive disorders in pregnancy than both natural conception and fresh embryo transfer (fresh-ET), but whether this is attributable to parental factors or treatment is unknown.

METHODS

Using the Medical Birth Registries of Denmark (1994-2014), Norway, and Sweden (1988-2015), linked to data from national quality registries and databases on assisted reproduction, we designed a population-based cohort study with within-sibship comparison. We included 4 426 691 naturally conceived, 78 300 fresh-ET, and 18 037 frozen-ET singleton pregnancies, of which 33 209 sibships were conceived using different conception methods. Adjusted odds ratios (aOR) of hypertensive disorders in pregnancy for fresh-ET and frozen-ET versus natural conception with 95% CI were estimated using multilevel logistic regression, where random effects provided conventional population-level estimates and fixed effects gave within-sibship estimates. Main models included adjustment for birth year, maternal age, parity, and country.

RESULTS

Risk of hypertensive disorders in pregnancy was higher after frozen-ET compared to natural conception, both at population-level (7.4% versus 4.3%, aOR, 1.74 [95% CI, 1.61-1.89]) and within sibships (aOR, 2.02 [95% CI, 1.72-2.39]). For fresh-ET, risk was similar to natural conception, both at population-level (aOR, 1.02 [95% CI, 0.98-1.07]) and within sibships (aOR, 0.99 [95% CI, 0.89-1.09]).

CONCLUSIONS

Frozen-ET was associated with substantially higher risk of hypertensive disorders in pregnancy, even after accounting for shared parental factors within sibships.

Obstetric, neonatal, and child health outcomes following embryo biopsy for preimplantation genetic testing

BACKGROUND

Preimplantation genetic testing (PGT) of embryos developed in vitro requires a biopsy for obtaining cellular samples for the analysis. Signs of cell injury have been described in association with this procedure. Thus, the consequences of the biopsy on obstetric and neonatal outcomes have been the subject of some quantitative analyses, although the reliability of data pooling may be limited by important issues in the various reports.

OBJECTIVE AND RATIONALE

The present review identifies evidence for whether pregnancies conceived after embryo biopsy are associated with a higher risk of adverse obstetric, neonatal, and long-term outcomes. Available evidence has been summarized considering manipulation at various stages of embryo development.

SEARCH METHODS

We used the scoping review methodology. Searches of article databases were performed with keywords pertaining to the embryo biopsy technique and obstetric, neonatal, and postnatal outcomes. Studies in which embryos were biopsied at different stages (i.e. both at the cleavage and blastocyst stages) were excluded. We included data on fresh and frozen embryo transfers. The final sample of 31 documents was subjected to qualitative thematic analysis.

OUTCOMES

Sound evidence is lacking to fully address the issues on the potential obstetric, neonatal or long-term consequences of embryo biopsy. For polar body biopsy, the literature is too scant to draw any conclusion. Some data, although limited and controversial, suggest a possible association of embryo biopsy at the cleavage stage with an increased risk of low birthweight and small for gestational age neonates compared to babies derived from non-biopsied embryos. An increase in preterm deliveries and birth defects in cases of trophectoderm biopsy was suggested. For both biopsy methods (at the cleavage and blastocyst stages), an increased risk for hypertensive disorders of pregnancy was found. However, these findings may be explained by confounders such as other embryo manipulation procedures or by intrinsic patient or population characteristics.

WIDER IMPLICATIONS

Since there is inadequate evidence to assess obstetric, neonatal, and long-term health outcomes following embryo biopsy, an invasive PGT strategy should be developed with a cautious approach. A non-invasive approach, based on the analysis of embryo cell-free DNA, needs to be pursued to overcome the potential limitations of embryo biopsy.

Time to pregnancy and perinatal outcomes in a cohort of spontaneous pregnancies

BACKGROUND

Obstetric and perinatal outcomes depend not only on care during pregnancy, as there is an increasing evidence of their relationship with preexisting conditions. Woman's age and time to pregnancy (TTP) have been related to the prognosis in reproductive success, but TTP could influence fetal well-being and newborn. According to the World Health Organization, 48 million couples have subfertility globally.

METHODS

We analyzed the relationship between TTP and obstetric (premature labor, preeclampsia…), labor (type of delivery, postpartum hemorrhage…), and neonatal outcomes (low birth weight…) in a cohort of 190 spontaneous gestations. Subfertility is a disease defined by the failure to achieve a pregnancy after 12 months of regular unprotected sexual intercourse.

RESULTS

TTP was >12 months in 23.1 % (95 % CI = 17.57-29.55), however, no correlation was found with the perinatal outcomes (p = 0.24). We observed that 45.2 % of subfertile women had obstetric complications, 13.2 % labor complications, and 34.2 % neonatal complications, whereas non-subfertile women had 29.4 %, 21.0 %, and 21.0 %, respectively. Half of pregnancies have at least one adverse outcome, and obstetric complications were the most frequent.

CONCLUSION

Subfertility condition may appear in up to a fifth of our couples. Subfertility may behave as a mild risk factor for adverse perinatal outcomes. Obstetric or perinatal complication may be expected in up to half of the cases. Subfertile women ≥ 35 years of age have a 3-fold increase in their risk of having an obstetric complication when compared to non-subfertile women of the same age.

History of infertility and pregnancy outcomes in Project Viva: a prospective study

Background

Infertility has been associated with the risk of adverse pregnancy outcomes. It is not clear whether infertility and underlying causes of infertility or the use of medically assisted reproduction (MAR) therapies are responsible for the observed associations. In this study, we aimed to evaluate the association of history of infertility with pregnancy outcomes and identify whether the associations, if present, differed by subgroups defined by the use of MAR.

Methods

Prospective study of 2201 pregnant women from the Boston-area Project Viva cohort. The exposure was history of infertility based on self-reported time to pregnancy ≥12 mo (or ≥ 6 mo if ≥35 y) or use of MAR; a diagnosis of infertility or claims for infertility treatments from medical records. The outcomes included: gestational glucose tolerance (gestational diabetes, impaired glucose tolerance, isolated hyperglycemia vs. normoglycemia), hypertensive disorders (gestational hypertension/preeclampsia vs. normotension), gestational weight gain (inadequate/excessive vs. adequate), systolic (SBP) and diastolic blood pressure, birthweight-for-gestational age z-score (tertile 2 and 3 vs. 1), preterm birth (<37 vs. ≥37 weeks at delivery), and birth outcome (pregnancy loss vs. live birth). We performed linear and logistic/multinomial regression analyses adjusted for age, race/ethnicity, age at menarche, pre-pregnancy BMI, and prenatal smoking.

Results

Mean (SD) age was 32.0 (5.0) years, and 18.8% of women had history of infertility, 32.6% of whom used MAR. SBP across pregnancy was 0.72 mmHg higher in women with vs. without infertility (95% CI 0.02, 1.42). The associations were stronger among women who used MAR (β 1.32 mmHg, 95% CI 0.21, 2.44), especially among those who used gonadotropins or gonadotropin-releasing hormone [GnRH] agonists (β 1.91 mmHg, 95% CI 0.48, 3.35). Other outcomes were not associated with history of infertility.

Conclusions

A history of infertility was associated with higher SBP during pregnancy, with stronger associations among those who used gonadotropins or GnRH agonists. Future studies are needed to confirm these findings and determine their clinical implications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04885-8.

Assisted reproductive technologies and the risk of stillbirth in singleton pregnancies: a systematic review and meta-analysis

OBJECTIVE

To identify the risk of stillbirth from in vitro types of assisted reproductive technologies compared with spontaneous conception (SC), limited to singleton births.

DESIGN

Systematic literature search and search chaining on online databases: PubMed, Embase, and Scopus.

SETTING

Not applicable.

PATIENT(S)

Singleton pregnancies from in vitro fertilization (IVF) or fertilization by IVF and intracytoplasmic sperm injection (IVF-ICSI).

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Adjusted odds ratio for stillbirth or prevalence of stillbirth in case-control groups of IVF/IVF-ICSI singletons and SCs, respectively, in matched studies.

RESULT(S)

A total of 19 studies were included, and study quality was mixed. Ten studies qualified for inclusion to the meta-analysis, which revealed a significantly increased risk of stillbirth in IVF/IVF-ICSI compared with that in SC (odds ratio [95% confidence interval]: 1.82 [1.37-2.42]), and there was no evidence of publication bias.

CONCLUSION(S)

In vitro fertilization and IVF-ICSI treatment increases the risk of stillbirth compared with natural conception.

CLINICAL TRIAL REGISTRATION NUMBER

PROSPERO 216768.

Time-to-pregnancy and risk of cardiovascular disease among men and women

A few studies indicate that women with prolonged time-to-pregnancy (TTP) have an increased risk of cardiovascular disease (CVD). This has not been studied in men. We evaluated CVD risk by self-reported TTP among parous women (n = 64,064) and men (n = 50,533) participating in the Norwegian Mother, Father and Child Cohort Study. TTP was categorized as 0–3 (reference), 4–12 and > 12 months. CVD diagnosed between 2008 and 2017 were available from the national patient and general practitioner databases. Risk of CVD by TTP was estimated using Cox regression adjusting for baseline age, education, BMI, smoking, diabetes, and number of offspring in both sexes, and history of endometriosis, ovarian cysts, preterm birth and pre-eclampsia for women. Mean age was 33 for women and 35 for men at baseline (years). The rate of any CVD was 24 per 1000 person years among women and 22 per 1000 person years among men. Longer TTP was associated with increased rate of CVD among women, with adjusted hazard ratios (HRs) of 1.07 (95% CI: 1.03, 1.09) for TTP 4–12 months and 1.14 (1.08, 1.20) for TTP > 12 months. Among men, respective HRs for CVD were 1.06 (1.00, 1.10) for TTP 4–12 months and 1.07 (1.01, 1.14) for TTP > 12 months. We observed sex-differences in the relationship with CVD subtypes but none were statistically significant. In conclusion, both men and women with a prolonged TTP had a small increased risk of CVD, clinical significance of which is unclear. Further studies are necessary to investigate in detail what underlying causes of prolonged TTP might be reflected in the increased risk of CVD. Longer follow-up is required to confirm these preliminary findings.

The non-traditional and familial risk factors for preeclampsia in the FINNPEC cohort

OBJECTIVES

Considering the burden of preeclampsia (PE), it is important to understand better the underlying risk factors involved in its etiology. We studied the association of background factors with PE with an emphasis on socioeconomic factors, reproductive factors and health history enclosing the parents of pregnant women.

STUDY DESIGN

The Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) cohort participants filled in a questionnaire on background information. The questionnaire data was available from 708 women with PE and 724 control women. Two different control groups, healthy controls with uncomplicated pregnancies (n = 498) and all controls (n = 724, including controls with uncomplicated pregnancies and pregnancy complications other than PE), were established.

RESULTS

PE women had similar socioeconomic status and more often non-communicable diseases including type 1 diabetes, chronic hypertension and hyperlipidemia than the two control groups (p < 0.05 for all). Depression and subfertility were more common among PE women and they had earlier menarche (p < 0.05 for all). Hypertension was more common in both parents of PE women, stroke in fathers and diabetes in mothers (p < 0.05 for all). Mental disorders including depression were more common in mothers of PE women compared to controls (PE women 7.2%, healthy controls 3.7% (p = 0.013) and all controls 3.9% (p = 0.007)).

CONCLUSIONS

In the FINNPEC cohort, PE women had similar socioeconomic status, more non-communicable diseases and depression, earlier menarche, more subfertility and more parental non-communicable diseases compared to controls. As a novel finding we found more mental disorders including depression in mothers of PE women.

Risk of preterm delivery in singletons conceived by in vitro fertilization

To evaluate the preterm delivery and other obstetrics complications similar in singleton pregnancies achieved through IVF compared to spontaneous pregnancies. Retrospective case-control study included 1663 women with singleton pregnancies following IVF-ICSI (study group) and 3326 women with singleton spontaneous pregnancies (control group) who delivered between January 2015 and January 2018 at the Peking University Third Hospital. The control group matched 1:2 by age, BMI, parity, and gravidity. Maternal outcomes included preterm delivery and complications. There was significantly higher incidence of gestational diabetes, hypertensive disorders, and placenta previa in IVF-ICSI pregnancies versus controls (p < .05). IVF-ICSI resulted in significantly higher rate of preterm birth than in spontaneous pregnancies (p < .05) and the difference remained significant for deliveries that occurred before 28, 32, and 34 weeks gestation (p < .05). Multivariate logistic regression analysis revealed that female-factor infertility, hypertensive disorder, placenta previa, and PROM were significant prognostic factors associated with increased risk of prematurity. IVF-ICSI is associated with increased risk of obstetric complications including preterm delivery in singleton pregnancies. Female-factor infertility is an independent prognostic factor for preterm birth. This information is important for patient counseling and helps to refine the recommendation to optimize maternal health before embarking on fertility treatments.

Assisted reproductive technology and the risk of preeclampsia: an updated systematic review and meta-analysis

Background

The objective of this systematic review and meta-analyses was to assess the risk of preeclampsia among women who conceived with assisted reproductive technology (ART).

Methods

We searched the ISI Web of Knowledge, Medline/PubMed, Scopus, and Embase (from inception to May 2017) for English language articles using a list of key words. In addition, reference lists from identified studies and relevant review articles were also searched. Data extraction was performed by two authors, and the study quality was assessed using the Newcastle–Ottawa Scale. Random-effects model meta-analysis was applied to pool the relative risks (RR) across studies.

Results

A total of 48 studies (5 case-control studies and 43 cohort studies) were included in this meta-analysis. The Cochran Q test and I² statistics revealed substantial heterogeneity (Q = 26,313.92, d.f. = 47, p < 0.001 and I² = 99.8%). Meta-analysis showed a significant increase in preeclampsia in women who conceived by ART compared with those who conceived spontaneously (RR = 1.71, 95% CI = 1.11–2.62, p = 0.015).

Conclusions

The findings of this systematic review indicate that the use of ART treatment is associated with a 1.71-fold increase in preeclampsia.

Risk of preeclampsia following assisted reproductive technology: systematic review and meta-analysis of 72 cohort studies

Objective: Previous studies have indicated that women with assisted reproductive technology (ART) pregnancy have an increased risk of preeclampsia. The aim of this current study was to estimate, through a systematic review and meta-analysis of cohort studies, the risk of preeclampsia in women who conceived with ART.Materials and methods: We searched ISI Web of Knowledge, Medline/PubMed, Scopus and Embase up to August 2017 for English-language articles pertaining to risk of preeclampsia in ART pregnancy using standard keywords. Data extraction was conducted by two authors and quality of the studies was assessed using the Newcastle-Ottawa Scale. A random-effects model was used for the meta-analysis.Results: In total, 72 cohort studies (n = 164 870) were included. The results of Cochran test and I² statistic indicated considerable heterogeneity among studies (Q = 15 415.61, df = 71, p < .001, I²=99.5%). The pooled estimate of preeclampsia risk using the random effects model was 10.8% (95% CI: 9.10-12.5). Furthermore, the funnel plot and Begg's test showed evidence of publication bias.Conclusions: We found that the risk of preeclampsia was very high among women who conceived with ART. Women should be counseled carefully before undergoing ART treatment.

Adverse pregnancy, birth, and infant outcomes in twins: effects of maternal fertility status and infant gender combinations; the Massachusetts Outcomes Study of Assisted Reproductive Technology

BACKGROUND

It is unknown whether the risk of adverse outcomes in twin pregnancies among subfertile women, conceived with and without in vitro fertilization, differs from those conceived spontaneously.

OBJECTIVE

We sought to evaluate the effects of fertility status on adverse perinatal outcomes in twin pregnancies on a population basis.

STUDY DESIGN

All twin live births of ≥22 weeks' gestation and ≥350 g birthweight to Massachusetts resident women in 2004 through 2010 were linked to hospital discharge records, vital records, and in vitro fertilization cycles. Women were categorized by their fertility status as in vitro fertilization, subfertile, or fertile, and by twin pair genders (all, like, unlike). Women whose births linked to in vitro fertilization cycles were classified as in vitro fertilization; those with indicators of subfertility but without in vitro fertilization treatment were classified as subfertile; all others were classified as fertile. Risks of 6 adverse pregnancy outcomes (gestational diabetes, pregnancy hypertension, uterine bleeding, placental complications [placenta abruptio, placenta previa, and vasa previa], prenatal hospitalizations, and primary cesarean) and 9 adverse infant outcomes (very low birthweight, low birthweight, small-for-gestation birthweight, large-for-gestation birthweight, very preterm [<32 weeks], preterm, birth defects, neonatal death, and infant death) were modeled by fertility status with the fertile group as reference, using multivariate log binomial regression and reported as adjusted relative risk ratios and 95% confidence intervals.

RESULTS

The study population included 10,352 women with twin pregnancies (6090 fertile, 724 subfertile, and 3538 in vitro fertilization). Among all twins, the risks for all 6 adverse pregnancy outcomes were significantly increased for the subfertile and in vitro fertilization groups, with highest risks for uterine bleeding (adjusted relative risk ratios, 1.92 and 2.58, respectively) and placental complications (adjusted relative risk ratios, 2.07 and 1.83, respectively). Among all twins, the risks for those born to subfertile women were significantly increased for very preterm birth and neonatal and infant death (adjusted relative risk ratios, 1.36, 1.89, and 1.87, respectively). Risks were significantly increased among in vitro fertilization twins for very preterm birth, preterm birth, and birth defects (adjusted relative risk ratios, 1.28, 1.07, and 1.26, respectively).

CONCLUSION

Risks of all maternal and most infant adverse outcomes were increased for subfertile and in vitro fertilization twins. Among all twins, the highest risks were for uterine bleeding and placental complications for the subfertile and in vitro fertilization groups, and neonatal and infant death in the subfertile group. These findings provide further evidence supporting single embryo transfer and more cautious use of ovulation induction.

Pregnancy, birth, and infant outcomes by maternal fertility status: the Massachusetts Outcomes Study of Assisted Reproductive Technology

BACKGROUND

Births to subfertile women, with and without infertility treatment, have been reported to have lower birthweights and shorter gestations, even when limited to singletons. It is unknown whether these decrements are due to parental characteristics or aspects of infertility treatment.

OBJECTIVE

The objective of the study was to evaluate the effect of maternal fertility status on the risk of pregnancy, birth, and infant complications.

STUDY DESIGN

All singleton live births of ≥22 weeks' gestation and ≥350 g birthweight to Massachusetts resident women in 2004-2010 were linked to hospital discharge and vital records. Women were categorized by their fertility status as in vitro fertilization, subfertile, or fertile. Women whose births linked to in vitro fertilization cycles from the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System were classified as in vitro fertilization. Women with indicators of subfertility but not treated with in vitro fertilization were classified as subfertile. Women without indicators of subfertility or in vitro fertilization treatment were classified as fertile. Risks of 15 adverse outcomes (gestational diabetes, pregnancy hypertension, antenatal bleeding, placental complications [placenta abruptio and placenta previa], prenatal hospitalizations, primary cesarean delivery, very low birthweight [<1500 g], low birthweight [<2500 g], small-for-gestation birthweight [z-score ≤-1.28], large-for-gestation birthweight [z-score ≥1.28], very preterm [<32 weeks], preterm [<37 weeks], birth defects, neonatal death [0-27 days], and infant death [0-364 days of life]) were modeled by fertility status with the fertile group as reference and the subfertile group as reference, using multivariate log binomial regression and reported as adjusted risk ratios and 95% confidence intervals.

RESULTS

The study population included 459,623 women (441,420 fertile, 8054 subfertile, and 10,149 in vitro fertilization). Women in the subfertile and in vitro fertilization groups were older than their fertile counterparts. Risks for 6 of 6 pregnancy outcomes and 6 of 9 infant outcomes were increased for the subfertile group, and 5 of 6 pregnancy outcomes and 7 of 9 infant outcomes were increased for the in vitro fertilization group. For 4 of the 6 pregnancy outcomes (uterine bleeding, placental complications, prenatal hospitalizations, and primary cesarean) and 2 of the infant outcomes (low birthweight and preterm) the risk was greater in the in vitro fertilization group, with nonoverlapping confidence intervals to the subfertile group, indicating a substantially higher risk among in vitro fertilization-treated women. The highest risks for the in vitro fertilization women were uterine bleeding (adjusted risk ratio, 3.80; 95% confidence interval, 3.31-4.36) and placental complications (adjusted risk ratio, 2.81; 95% confidence interval, 2.57-3.08), and for in vitro fertilization infants, very preterm birth (adjusted risk ratio, 2.13; 95% confidence interval, 1.80-2.52), and very low birthweight (adjusted risk ratio, 2.15; 95% confidence interval, 1.80-2.56). With subfertile women as reference, risks for the in vitro fertilization group were significantly increased for uterine bleeding, placental complications, prenatal hospitalizations, primary cesarean delivery, low and very low birthweight, and preterm and very preterm birth.

CONCLUSION

These analyses indicate that, compared with fertile women, subfertile and in vitro fertilization-treated women tend to be older, have more preexisting chronic conditions, and are at higher risk for adverse pregnancy outcomes, particularly uterine bleeding and placental complications. The greater risk in in vitro fertilization-treated women may reflect more severe infertility, more extensive underlying pathology, or other unfavorable factors not measured in this study.