Endocrine interactions in the control of fetal growth

Hormones are both growth stimulatory and growth inhibitory in utero. They act as environmental and maturational signals in regulating tissue accretion and differentiation during late gestation. They ensure that fetal development is appropriate for the nutrient supply and is optimal for neonatal survival. Growth-stimulatory hormones, such as insulin, the insulin-like growth factors and the thyroid hormones, have anabolic effects on fetal metabolism and increase cellular nutrient uptake and energy production for tissue accretion. Thyroid hormones also have specific effects on tissue differentiation at key developmental milestones. Similarly, leptin appears to affect development of specific fetal tissues and may counterbalance the maturational actions of other hormones near term. Glucocorticoids inhibit growth in utero but are essential for prepartum tissue differentiation in preparation for delivery. They also affect fetal bioavailability of most of the other growth-regulatory hormones. In addition, many of these hormones alter the placental capacity to supply nutrients for fetal growth. In producing a fetoplacental epigenome specific to the prevailing intrauterine environment, hormones interact to produce phenotypical diversity with potential health consequences long after birth.