The outcomes of surrogate pregnancy using donor egg compared to surrogate's egg: a systematic review

Surrogacy is either gestational (GS) using donor egg or traditional (TS) using surrogate's own egg. GS is increasing, partly from assumptions over less difficulty in transferring the baby to intended parents. This systematic review investigates obstetric outcomes in GS vs TS and vs surrogate's own spontaneous conceptions (SC), comparing genetically unrelated embryos versus genetically related embryos.

Included were studies with historical or concurrent GS to TS or to SC comparisons, reporting any obstetric outcomes. MEDLINE, Embase, Global Health, and PsycINFO databases were searched to October 2024, 34 specialist surrogacy researchers' publications assessed. Citations, data extraction, and quality assessment were conducted in duplicate. Results tabulated, and random-effects meta-analysis using relative risks (RR) conducted (Cochrane Revman software version 5.4.1).

From 937 records, eight studies were included, four each in singleton pregnancies comparing GS to TS and TS to SC. GS to TS studies were small with imprecise results on obstetric and mental health outcomes. GS to SC studies showed worse pre-eclampsia/gestational hypertension (RR = 2.39 (95% CI = 1.15-4.49)), gestational diabetes (RR = 4.68 (95% CI = 1.53-14.25)), and pre-term birth (RR = 3.18 (95% CI = 1.64-6.14)).

Current best available evidence is sparse but suggests higher rates of adverse obstetric and birth outcomes in GS pregnancies, concurring with donor egg non-surrogacy pregnancy research, and underlying causes are likely genetic. More research is needed comparing GS to TS and to SC and reporting singleton and twin pregnancy results. All parties considering GS should be informed of higher maternal and neonatal complication rates.