Early Determinants of Child Health

There has been long-standing concern, from couples and health care providers, that children conceived using fertility treatment grow and develop differently than children not conceived by these technologies. Some of the concern stems from observations that children conceived by assisted reproductive technologies (ART) have lower birthweight and gestational age, known risk factors for many later health outcomes. The increased risk that these perinatal outcomes confer for heart disease, along with elevated blood pressure, has been particularly consistent across different populations. Mechanisms specific to ART include the potential for epigenetic changes during the implementation of these technologies, including culture media. Using the Upstate KIDS cohort, we previously evaluated the long-term cardio-metabolic risk of children conceived by fertility treatment, both by ART and by fertility drugs, finding no differences [Yeung et al. Fertil Steril 2022;121:793]. Due to the smaller number of children agreeing to Upstate KIDS clinic visits hailing from all over New York State, the findings were pursued using the larger cohort of children with information from 7–9 years as reported by mothers at their physician visits [Reference 1]. The results remained similar, with no concerns for BMI or blood pressure after conception using fertility treatments. Overall, the body of evidence from Upstate KIDS has reassured parents and clinicians that ART in particular do not lead to detriments in childhood health.

In collaboration with international researchers in the Pregnancy And Childhood Epigenetics (PACE) consortium, we participated in several investigations of newborn and childhood DNA methylation to decipher how they may explain differences in development and child health. These studies examined how experiences during pregnancy may affect how genes work in newborn babies and children. One study confirmed that maternal sustained smoking during pregnancy contributes to unique newborn DNA methylation signatures. However, paternal smoking, other secondhand smoke, or maternal past smoking all contributed to fewer apparent differences in DNA methylation at birth in blood samples [Reference 2]. Another study found that mothers with asthma during pregnancy were more likely to have babies with DNA methylation changes linked to genes involved in lung health and asthma risk [Reference 3]. The team continues to lead a project following on previous findings on the impact of parental age on DNA methylation and to contribute to other investigations in the consortium.

Early complementary feeding may have consequences for subsequent eating habits and childhood growth. Understanding these relationships may inform better evidence-based guidelines on when to introduce and feed certain foods in infancy. We previously confirmed the findings that breastfeeding and delaying introduction of certain complementary foods is associated with long-term childhood body mass index (BMI). In 2025, using Upstate KIDS data, we examined whether timing of introducing certain foods such as fruits and vegetables affected the child's own intake of such and their overall dietary patterns before (three years old) and after school age (seven to nine years old). We evaluated dietary patterns according to a composite Youth Healthy Eating Index score, with higher scores denoting better diet quality (e.g., more fruits and vegetables, less sugar-sweetened beverages, etc.). We found that waiting too long to introduce some food items such as fruits and vegetables was associated with lower daily intake. It was also in turn associated with lower diet quality [Reference 4]. These findings suggest that decisions around when to introduce healthy foods can have longer-term consequences.

However, the timing of introduction of complementary foods is complicated by the many recommendations that are available. The American Academy of Pediatrics recommends introduction around six months of age, but many parents base decisions on other factors such as signs of development. From over 5,400 children with information in Upstate KIDS, we found that signs of developmental readiness contributed to earlier introduction to complementary foods than the recommended age of feeding at six months [Reference 5]. Factors included whether they could sit without support, reached for items, frequently put items in their mouths, had a good appetite, or had steady head control, factors that individually and in combination were associated with higher likelihood of introducing complementary foods and beverages before six months. While racial differences in the timing of complementary feeding were observed, the perceived developmental readiness of infants played a role in these differences. That raises the question as to how best to create clear and consistent guidance on which developmental signs matter most to support healthy habits and long-term growth.

We continued to recruit couples into the Study of Pregnancy and Neonatal Health (SPAN) at four study sites, in order to investigate paternal contributions to the developmental origins of health and disease. While much research has been devoted to maternal exposures, information on paternal factors is greatly lacking, despite evidence of potential epigenetic pathways in animal models. The data collected will uniquely answer important questions about how paternal obesity and other cardio-metabolic risk factors affect fetal growth, placental factors, and neonatal outcomes.