411 - The Impact of In Vitro Fertilization on Birth Weight and Fetal Growth in Singleton Pregnancies

Poster Number: 411
Publication Number: 411.135

Erika Lin, University of California, San Diego School of Medicine, San Diego, CA, United States; Aruna Ayalasomayajula, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, United States; Rekha Karuparthy, Ann & Robert H. Lurie Children's Hospital of Chicago, Bettendorf, IA, United States; Linda M. Ernst, University of Chicago Division of the Biological Sciences The Pritzker School of Medicine, Evanston, IL, United States; Emin Maltepe, UCSF, San Francisco, CA, United States; Karen Mestan, University of California, San Diego School of Medicine, San Diego, CA, United States

Background: In vitro fertilization (IVF), a form of assisted reproductive technology (ART), involves egg retrieval and fertilization by sperm ex vivo followed by fertilized embryo transfer to the uterus. Despite multiple studies evaluating the relationship between IVF and clinical outcomes, the results vary. Thus, the potential risks of IVF are not universally acknowledged for mothers and infants.

Objective: To investigate relationships between maternal and neonatal covariates in IVF singleton pregnancies

Design/Methods: Data on 31,318 births between March 2018 – October 2019 were retrospectively queried from the Northwestern Medicine Enterprise Data Warehouse (NMEDW). Among singleton pregnancies (n=29,980), 292 VIF and 29,041 control (non-IVF) pregnancies were confirmed and further matched 1:1 by maternal age and gestational age (GA) at delivery to minimize the confounding effects discovered in the larger sample. The matched cohort included 246 IVF and 246 control singletons.

Results: In the unmatched cohort of 29,980 births, maternal race, gravida BMI, rates of c-section, preeclampsia, and gestational diabetes were significantly different. Maternal age was higher among IVF mothers, whereas, GA was higher among non-IVF births. Birth weight (BW) and small-for-gestational age ( < 10th percentile) were not significantly different. When matched by maternal age and GA, there were no significant differences among several maternal factors including race, delivery method, pregravida BMI, preeclampsia, chronic hypertension, asthma, and diabetes. Maternal ethnicity (p < 0.001), gravida BMI (26.9 ± 6.4 kg/m2 vs. 29.9 ± 6.3 kg/m2; IVF vs. control; p< 0.001), BW (3332 ± 595 g vs. 3172 ± 589 g; IVF vs. control; p=0.003) were different between groups, with infants conceived via IVF having higher mean BW-for-GA percentile (53.8 ± 26.7 vs. 44.9 ± 27.4; p=0.0003) and lower SGA status (4.5% vs. 13%; IVF vs. control; p =0.002). Stratification by completed weeks of gestation revealed that the association between IVF and increased BW was strongest after 36 weeks (Table 1; Figure 2).Conclusion(s): Previous reports of IVF pregnancy on birth weight have not matched by GA to isolate the role of IVF on perinatal outcomes. IVF mothers had lower gravida BMI, yet they gave birth to larger infants. Further investigation into the impact of IVF on fetal growth is warranted.
Figure 1Birth weight in preterm ( 36 weeks) births in matched cohort.
Table 1Mean and median birth weights and birth weight percentiles among preterm vs. term births in matched cohort.