Breastfeeding and History of Infertility
by Anne Eglash MD, IBCLC, FABM
Lactation specialists often assume that infertility is associated with low milk production or early weaning. These observations are typically attributed to the demographics of those undergoing assistive reproductive technology (ART) because these individuals are often older first time parents, and have a higher risk of pregnancy complications such as multiple, cesarean, or premature births. However, there has not been rigorous evidence available to support these observations.
A 2015 Italian cohort study evaluated 173 singletons born after ART (homologous in vitro fertilization and embryo transfer), who were 34+ weeks gestation, and who were matched one-to-one with infants of similar demographics who were not born after ART. Although both groups had equal initiation rates of approximately 90%, the researchers found that the women who conceived via ART were more likely to wean by 6 weeks postpartum vs those who conceived naturally (20.2% vs 5.3%).
Fast forward to 2022- the study for this week explored pregnancy and delivery complications as possible mediators of the lower breastfeeding rates among those who undergo ART. This was a retrospective cohort study among women who had live births in a medical center in northern Taiwan from January 2014-December 2018 that was associated with a Baby Friendly Certified hospital. A sample of 3650 women were categorized into one of three groups: 1) fertile women who conceived naturally, n=2857, or 78.3%, 2) sub-fertile women who conceived naturally after trying for 12 months, n=483 or 13.2% and 3) infertile women who conceived via ART, n=310, 8.5%.
The women who were sub-fertile or infertile were more likely to be older, primiparous, have a history of abortion, and pre-existing diseases as compared to fertile women. They found that the sub-fertile and infertile women had similar intention and initiation of breastfeeding compared to those who were fertile but had a shorter duration of exclusive breastfeeding with earlier introduction of formula in the first week postpartum compared to fertile women. They did not stop breastfeeding earlier than the fertile group.
What else? See the question!
- Multiple gestation
- Admission to NICU
- Low birth weight
- Preterm birth
- Delivery complications
See the Answer
It is uncertain whether Assisted Reproductive Technology (ART) is associated with an increased risk of poor breastfeeding outcomes and what could be possible mechanisms. This study aimed to examine the effect of mode of conception on breastfeeding outcomes during the first two months postpartum and identify the potential mediating pathways for this relationship.
A retrospective cohort study was conducted in a sample of 3,565 women with live births. Participants were classified by mode of conception as follows: fertile women who conceived naturally (fertile women; n = 2,857), women with infertility who conceived naturally (sub-fertile women; n = 483), and women with infertility who conceived through ART (women with infertility; n = 310). The infant-feeding patterns were assessed with four-time points before two months postpartum. Binary and multinomial logistic regression and causal mediation analyses were performed.
The rates of breastfeeding initiation and discontinuation across modes of conception were similar. However, infertile and sub-fertile women had 37% (95% CI 1.02, 1.83) and 56% (95% CI 1.06, 2.27) increased risks of introducing formula before the first week postpartum, respectively, and 35% (95% CI 1.01, 1.82) and 52% (95% CI 1.04, 2.24) higher risks of exclusive breastfeeding for less than one week, respectively, compared to fertile women. The relationships were mainly mediated through multiple gestation and admission to neonatal/pediatric intensive care units (NICU/PICU; proportions of mediation were over 50%). The effects of mode of conception on breastfeeding outcomes became not significant in cases of singleton birth.
Sub-fertile women and women with infertility intended to breastfeed but experienced higher perinatal risks in the early postpartum period. Multiple gestation and admission to NICU/ PICU forced them to introduce formula earlier than preferred, thus leading to a shorter duration of exclusive breastfeeding. Single embryo transfer policy and breastfeeding support in NICU/PICU could help those women achieve positive early breastfeeding outcomes.
This study confirmed what we have been suspecting. The higher likelihood of formula introduction in the first week among mothers undergoing ART is not associated with intention to breastfeed, but the complications of pregnancy and delivery, namely premature birth, NICU admission, multiple gestation, low birth weight, and delivery complications which included premature rupture of membranes, abruptio placentae, placenta previa, postpartum hemorrhage, prolonged labor, prolapsed cord, etc.
Among the infertile women who introduced formula in the first week, the most likely reason was multiple gestation, which was an underlying reason for the other pregnancy and delivery complications. The authors shared that in Taiwan, 80% of people undergoing ART have at least 2 embryos implanted, and they recommended that transplanting just 1 embryo may be safer for families, to decrease the risk of complications and to increase exclusive breastfeeding rates.