Third-Trimester Placental Biomarkers and Their Link to Childhood ADHD Risk

A team from University of Iowa Health Care, publishing in JAMA Psychiatry, reports that placental growth factor (PlGF) levels that fail to climb in late pregnancy may point to a higher likelihood of ADHD in the child years down the road.

The placenta is responsible for supplying blood and nutrients to your baby, removing waste, and shielding against toxins and infections, and PlGF is one of the key proteins it makes. We've long known that low PlGF raises red flags for preeclampsia and other complications, but the Iowa group wanted to ask whether this same biomarker might also speak to how the developing brain is being shaped in utero. ADHD affects up to 10% of American children ages 3 to 17, and despite how common it is, we still have an incomplete picture of where the roots of the condition lie.

What the researchers actually measured

The team tapped into banked maternal blood samples from 176 pregnancies in the UI Department of Obstetrics and Gynecology's Perinatal Family Tissue Bank, measuring PlGF across all three trimesters. They then linked those samples to the children's later health records to see who went on to receive an ADHD diagnosis.

Here's what stood out, and it's the part that should change how we counsel patients: in pregnancies where the child was later diagnosed with ADHD, PlGF did not show the typical third-trimester rise we expect to see in a healthy pregnancy. In pregnancies that did not lead to an ADHD diagnosis, the biomarker climbed on schedule. Each standard-deviation drop in third-trimester PlGF was associated with 2.6 times higher odds of a later ADHD diagnosis in the child. The study showed no significant difference in PlGF levels in the first or second trimesters, so the signal really is a late-pregnancy phenomenon.

Why this matters for your third trimester

First author Serena (Banu) Gumusoglu, Ph.D., a UI assistant professor of obstetrics and gynecology and psychiatry, frames this as evidence that risk begins in utero and that the placenta may play a major role in shaping neurodevelopmental outcomes. The clinical takeaway for us in practice is that a third-trimester PlGF level, something we may already be tracking when preeclampsia is on the differential, could carry information that stretches far beyond the immediate pregnancy.

This doesn't mean a low PlGF number is a diagnosis of anything to come, and we want to be careful not to hand that worry to a patient without context. What it does mean is that when we see those third-trimester levels lagging, we have one more reason to take the conversation seriously, to loop in pediatric colleagues early, and to flag the family for closer developmental follow-up after delivery.

What to ask at your next visit

If you're in your third trimester and PlGF has come up in your bloodwork, especially if preeclampsia risk was already part of your picture, bring it into the room with your provider. Ask whether your PlGF levels showed the expected third-trimester rise, and if they didn't, ask what that might mean for both the remainder of your pregnancy and for postpartum pediatric surveillance. ADHD is highly treatable when caught early, and knowing that a placental signal existed simply gives us a head start on watching, not on worrying.