Children conceived by assisted reproduction technology (ART) are shorter and lighter at birth than those conceived naturally but have similar height and weight by age 17, according to a study published in Human Reproduction. Investigators conducted a prospective study involving 81,461 children from the Norwegian Mother, Father, and Child Cohort Study and 544,113 adolescents screened for military conscription to examine the growth pattern of children conceived by ART versus naturally conceived children. Children conceived by ART were shorter (boys, −0.3 cm; girls, −0.4 cm) and lighter (boys, −113 g; girls, −107 g) at birth. Children conceived by ART grew more rapidly after birth, achieving greater height and weight at age 3. Greater height up to age 7 was seen for children conceived by ART, but height and weight were no greater by age 17. Growth patterns similar to ART children were seen for naturally conceived children of parents taking a longer time to conceive. Larger ultrasound measures were seen for children born after frozen embryo transfer, and they were longer and heavier in the first 2 years compared with those born after fresh embryo transfer.
