Association of multifetal gestation with obstetric and neonatal outcomes in gestational carrier pregnancies

Obstetric Characteristics and Outcomes of Gestational Carrier Pregnancies: A Systematic Review and Meta-Analysis

Importance

Advancements in assisted reproductive technology (ART) have led to an increase in gestational carrier (GC) pregnancies. However, the perinatal outcomes of GC pregnancies remain understudied, necessitating a deeper understanding of their associated risks.

Objective

To assess maternal characteristics and obstetric outcomes associated with GC pregnancies.

Data Sources

A comprehensive systematic search of publications published before October 31, 2023, using PubMed, Web of Science, Scopus, and Cochrane Library databases was conducted.

Study Selection

Two authors selected studies examining obstetric characteristics and outcomes in GC pregnancies with 24 or more weeks' gestation. Studies with insufficient outcome information, unavailable data on gestational surrogacies, and non-English language studies were excluded.

Data Extraction and Synthesis

Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, 2 investigators extracted and synthesized both quantitative and qualitative data. Both fixed-effect and random-effect analysis were used to pool data.

Main Outcomes and Measures

The primary outcomes were obstetric characteristics and outcomes, including hypertensive disorders, preterm birth, and low birth weight. Secondary outcomes included severe maternal morbidity and mortality associated with GC pregnancies.

Results

Six studies from 2011 to 2023 involving 28 300 GC pregnancies and 1 270 662 non-GC pregnancies were included. GCs accounted for 2.5% of in vitro fertilization cycles (59 502 of 2 374 154 cycles) and 3.8% of ART pregnancies (26 759 of 701 047 ART pregnancies). GC pregnancies were more likely to be conceived by frozen embryo transfer compared with non-GC ART pregnancies (odds ratio [OR], 2.84; 95% CI, 1.56-5.15), and rates of single embryo transfer were similar between the 2 groups (OR, 1.18; 95% CI, 0.94-1.48). GCs were rarely nulliparous (6 of 361 patients [1.7%]) and were more likely to have multifetal pregnancies compared with non-GC ART patients (OR, 1.18; 95% CI, 1.02-1.35). Comparator studies revealed lower odds of cesarean delivery (adjusted OR [aOR], 0.42; 95% CI, 0.27-0.65) and comparable rates of hypertensive disorders (aOR, 0.86; 95% CI, 0.45-1.64), preterm birth (aOR, 0.82; 95% CI, 0.68-1.00), and low birth weight (aOR, 0.79; 95% CI, 0.50-1.26) in GC pregnancies vs non-GC ART pregnancies. Comparatively, GC pregnancies had higher odds of hypertensive disorders (aOR, 1.44; 95% CI, 1.13-1.84) vs general (non-GC ART and non-ART) pregnancies with comparable cesarean delivery risk (aOR, 1.06; 95% CI, 0.90-1.25). Preterm birth and low birth weight data lacked a comparative group using multivariate analysis. Severe maternal morbidity and maternal mortality were rare among GCs.

Conclusions and Relevance

In this systematic review and meta-analysis, although GC pregnancies had slightly improved outcomes compared with non-GC ART pregnancies, they posed higher risks than general pregnancies. Contributing factors may include ART procedures and increased rates of multiple gestations which influence adverse perinatal outcomes in GC pregnancies.

Examining pre-term birth and cesarean section rates in gestational carrier pregnancies

PURPOSE

This study sought to report on the route and gestational age at delivery of gestational carrier (GC) pregnancies with respect to the GCs' prior obstetric history.

METHODS

A retrospective analysis of all GC pregnancies from one of the largest surrogacy agencies in California between 2008 and 2018 was performed. Available demographic data and obstetric history, including a history of prior cesarean section (CS) and preterm birth (PTB), were collected for each GC and correlated to outcomes of the index GC pregnancy. Primary outcomes for the index GC pregnancies included delivery route and gestational age at delivery.

RESULTS

Eight-hundred-thirty-six GCs were included in our analysis. 319 (38.2%) delivered via CS, and 517 (61.8%) delivered vaginally. 60 (18.8%) of the CS deliveries were due to multifetal gestation. Primary CS rate in singleton GC pregnancies was 38.5%. In women without a history of CS, neither age, BMI, interpregnancy interval, prior parity, nor year of delivery impacted the primary singleton CS rate (all, P > 0.05). Of GCs with a history of a prior CS (n = 350, 41.9%), 218 (62.3%) had a vaginal delivery after CS (VBAC) and 132 (37.7%) had a repeat CS. Women who had successful VBACs were significantly younger than those who had repeat CS (mean 33.7 vs. 35.2 years, P = .003). BMI was lower in patients who had a VBAC compared to those that had a repeat CS (mean BMI 24.6 vs. 25.5, P = 0.074), although this did not reach statistical significance. In GCs with a history of CS, interpregnancy interval, year of delivery, prior parity, and multiple gestation in the index GC pregnancy did not impact mode of delivery. VBAC rates did not change over the study period (P = 0.757). Overall PTB rate was 15.1%. Most PTB in GC pregnancies were in those with a history of PTB, and PTB was more likely in singletons rather than multifetal gestations (76.7% in singletons vs. 30% in multiples) in patients with history of PTB (P < 0.001). Those with no history of PTB and who carried multiples had a low rate of PTB; in fact, in this group, only 1 out of 35 patients had a PTB with multiples.

CONCLUSIONS

Both primary CS and PTB rates in singleton GC pregnancies are higher than national averages. CS rates are independent of age, BMI, and interpregnancy interval. In GCs with a history of a CS, VBAC rates well exceed national averages and are higher in younger GCs with a lower BMI. PTB rates are impacted primarily by the GCs obstetric history. In those GCs without a history of PTB, rates of PTB are low, even in those with a multifetal gestation.