Child growth from birth to 18 months old born after assisted reproductive technology—Results of a national birth cohort study

BackgroundPregnancy conceived by assisted reproductive technology (ART) carries a higher risk of adverse birth outcomes. So far, there have been very few longitudinal studies of the growth of children born after ART.ObjectiveThe purpose of this study was to explore the determinants of growth of children born after ART.Design, setting and participantsUsing data of Wave I (6 months old) and II (18 months old) of the Taiwan Birth Cohort Study (TBCS), a national sample of 21,248 pairs of mothers and their children were included for analysis, including 366 pairs resulting from ART (1.7%).MethodsData were collected through field interviews with structured questionnaires, and with references to each child's birth certificate and Passport of Well-baby Care.ResultsCompared to children born with naturally conceived pregnancy, children born after ART had a significantly higher incidences of low birth weight (33.1 vs. 6.9%; p < 0.001) and prematurity (42.1 vs. 11.3%; p < 0.001). Overall children born after ART had a similar trend of growth in body weight from birth to 18 months old, but did not achieve catch-up of body weight by 18 months old. On the other hand, they had a faster growth and evidence of catch-up in both body height and head circumference from 6 months to 18 months old. Stratified by the birth number, for singleton or twin babies, there was no significant difference in most parameters of growth at birth and up to 18 months old between babies born by ART compared with those born through a natural conception. Analysis using generalized estimating equation modeling showed that multiple pregnancy and breastfeeding as well as having the mother herself as the caregiver in daytime through 18 months old are the negative and positive contributing factors, respectively for both growth and the change of growth with time among children born after ART.ConclusionThough exhibiting a higher incidence of low birth weight as well as prematurity, children born with ART enjoyed a similar or faster rate of growth from birth to 18 months old when compared to those children born through naturally conceived pregnancies. While multiple gestation is always a negative contributing factor, continuous breastfeeding and having the mother herself as the caregiver in daytime are positive contributing factors for the growth and/or change of growth for the children born after ART.