Perinatal outcomes in siblings from different conception methods: in vitro fertilization with autologous oocyte or donor egg vs. unassisted medical conception.

Objective: To study the perinatal outcomes of children born from different conception methods: in vitro fertilization (IVF) with autologous oocytes or IVF with donor egg vs. those conceived without medical assistance by using a sibling analysis.

Design: Retrospective cohort study conducted using electronic medical record data from 2000 through 2018, of a national healthcare organization.

Subjects: The cohort included mothers who had 2 pregnancies and their children. Cohort A compared women with 2 medically unassisted conceptions with those with an unassisted first conception followed by an IVF conception. Cohort B compared women with 2 medically unassisted conceptions with those with an unassisted conception followed by a second pregnancy from oocyte donation.

Exposure: None.

Main Outcome Measures: Perinatal outcomes, including small for gestational age (SGA) and preterm birth (PTB) at <37 weeks, were investigated. The secondary outcomes included low birth weight, very low birth weight, and large for gestational age (LGA).

Results: Cohort A comprised women who had 2 medically unassisted pregnancies and those with 1 medically unassisted pregnancy followed by IVF (n = 1,080 in each). Gestational age at delivery for the second conception was significantly lower in the unassisted + IVF group compared than in the medically unassisted group (38.1 ± 2.1 weeks vs. 39.1 ± 1.4 weeks). The unassisted + IVF group had higher rates of prematurity at <37 weeks (12% vs. 3.5%) and SGA than the medically unassisted group (5.4% vs. 3.4%). The adjusted odds ratio for PTB was 3.32 (95% confidence interval, 2.11-5.29), and that for SGA was 1.88 (95% confidence interval, 1.07-3.32). Cohort B included 94 women in each group. No differences were found between the medically unassisted and medically unassisted + donor egg groups regarding PTB at <37 weeks and SGA. The rate of LGA was higher in the egg donation group (24% vs. 16.5%).

Conclusions: This sibling analysis suggests that IVF pregnancies with autologous eggs are more susceptible to PTB, low birth weight, very low birth weight, and SGA, whereas donor egg pregnancies appear relatively unaffected, except for the higher rate of LGA.