The impact of conception by in vitro fertilization on breastfeeding initiation and establishment among singleton...

Breastfeeding has many benefits for mother and child. Previous studies have suggested that breastfeeding is highly desired in pregnancies conceived through in vitro fertilization, but that early breastfeeding cessation may be more common in this population. We aimed to study the effect of conception by in vitro fertilization on breastfeeding initiation, use of formula in hospital, and rates of exclusive breastfeeding at time of hospital discharge.

We conducted a retrospective cohort study of all women who gave birth to a live, singleton baby in Victoria, Australia from 2009 to 2017 (589,044 pregnancies, 19,220 (3.3%) in vitro fertilization-conceived). Exposure was conception with in vitro fertilization, compared with spontaneous conception. The primary outcomes included 1) breastfeeding initiation, 2) use of formula in hospital, and 3) exclusive breastfeeding on discharge. Two multivariable generalized linear regression models were analyzed. The first, adjusting for preconception confounding factors; maternal age, Socio-Economic Indexes for Areas, body mass index, smoking, and parity. The second, additionally adjusting for postconception mediators that may affect breastfeeding success; mode of birth, gestation, postpartum hemorrhage, hypertensive disorders, diabetes, birth in a private hospital, birthweight, low Apgars, and admission to the neonatal intensive care unit/special care nursery.

Breastfeeding initiation rates were high, regardless of mode of conception. After adjustment for preconception confounders, formula use in hospital increased by 26% among in vitro fertilization-conceived pregnancies (RR, 1.26%; 95% confidence interval, 1.24-1.29), and the chance of exclusive breastfeeding at discharge was reduced by 12% (RR, 0.88; 95% confidence interval, 0.87-0.89). After adjustment for all measured confounders and mediators, the magnitude of the impact of in vitro fertilization conception on breastfeeding difficulties was reduced but remained significant (use of formula in hospital: RR, 1.09; 95% confidence interval, 1.07-1.10; exclusive breastfeeding on discharge: RR, 0.92; 95% confidence interval, 0.91-0.93). Our findings suggest that there may be an independent impact of mode of conception on breastfeeding, but that the association is mediated in part by the higher rates of pregnancy and birth complications seen in women that use in vitro fertilization to conceive.

Women who conceive via in vitro fertilization are more likely to utilize formula while in hospital, and less likely to exclusively breastfeed at hospital discharge. Our research provides insights into the potential factors influencing differences in breastfeeding outcomes for in vitro fertilization-conceived pregnancies. Early lactation support for an in vitro fertilization-conceived cohort may improve long-term breastfeeding outcomes.