Surrogate mothers at high risk of morbidity, adverse pregnancy outcomes

Gestational carriers, or surrogate mothers, are at increased risk for severe maternal morbidity (SMM) and adverse pregnancy outcomes than women who conceived with and without assistance, reports a recent study.

“Although gestational carriage was associated with preterm birth, there was less clear evidence of severe neonatal morbidity,” the authors said.

All singleton births at more than 20-weeks' gestation in Ontario, Canada, from 2012 to 2021 were included in this population-based cohort study. Gestational carriage or surrogacy, the main exposure, was compared with unassisted conception and in vitro fertilization (IVF). 

The authors used modified Poisson regression models to generate weighted relative risks (wRRs) via propensity score-based overlap weighting.

SMM and severe neonatal morbidity (SNM) were the main outcomes, while secondary outcomes were hypertensive disorders of pregnancy, caesarean delivery, preterm birth, and postpartum haemorrhage.

Among the eligible singleton births, 806 (0.1 percent) were by gestational carriage, 16,087 (1.8 percent) by IVF, and 846,124 (97.6 percent) by unassisted conception. 

The risks for SMM were highest for gestational carriage (7.8 percent), followed by IVF (4.3 percent) and unassisted conception (2.3 percent). The wRR for gestational carriage was 3.30 (95 percent confidence interval [CI], 2.59–4.20) when compared with unassisted conception and 1.86 (95 percent CI, 1.36–2.55) when compared with IVF. 

For SNM, the risks were highest with IVF, followed by gestational carriage and unassisted conception. The wRR was 1.20 (95 percent CI, 0.92–1.55) for gestational carriage versus unassisted conception and 0.81 (95 percent CI, 0.61–1.08) for gestational carriage versus IVF.

At 37 weeks, the secondary outcomes were also significantly higher among surrogate mothers when compared with women who had unassisted conception or IVF.

“Potential mechanisms for higher maternal morbidity among gestational carriers require elucidation, alongside developing special care plans for gestational carriers,” the authors said. 

The study was limited by the absence of data on indications for choosing a gestational carrier and oocyte or sperm donor source.