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Our research, published in the journal AIDS, finds an association between babies with low birth weight and dysfunction in the arterioles of the placenta, particularly among mothers with HIV.
The placenta is a vital organ during pregnancy. It contains tiny blood vessels called arterioles that expand and contract to regulate the flow of blood to the developing fetus, ensuring the efficient exchange of nutrients and oxygen, as well as the removal of waste.
Proper placenta vessel function is crucial for normal fetal growth. Dysfunction can occur due to several reasons, including abnormal placental structure, problems with how the placenta attaches to the uterine lining, or maternal health factors, such as preeclampsia, diabetes, or infection.
A novel MedStar Health Research Institute study, published in the journal AIDS, newly identified an association between infants born small for gestational age (SGA) or less than the 10th percentile for weight, placental blood vessel dysfunction, and exposure to both maternal HIV and antiretroviral therapy (treatment for HIV).
Research has long shown that infants of mothers with HIV have as much as a 40% increased risk of SGA birthweight. SGA can lead to short- and long-term serious health concerns for the child.
Building on prior research done at MedStar Georgetown that showed HIV may impact the function of arterioles in the skin, we designed a study to evaluate if there’s a connection between fetal HIV exposure in the uterus, placental arteriolar function, and SGA birthweight.
A case-control study of placenta arteriole function.
Our case-control study involved 30 women, all of whom delivered between 36 and 41 weeks. Each mother-baby pair belonged to one of these groups:
- No HIV exposure, baby was normal birth weight (this functioned as our control group for comparison)
- No HIV exposure; baby was SGA
- HIV exposure, baby was normal birth weight
- HIV exposure, baby was SGA
After each baby in the study was delivered, we collected a sample of placental tissue. We analyzed the arterioles from each placenta’s intervillous space, where the exchange of fetal/maternal blood occurs. We used a myograph to measure the relaxation and contraction of blood in the arterioles, allowing us to determine whether the arterioles were reacting properly in response to stimuli.
When compared to our control group, we found that the blood vessels from placentas exposed to HIV contracted more and had more difficulty relaxing, even when babies were born with an appropriate birthweight for their gestational age. The same was true for the group with SGA but no HIV exposure. Placentas from mothers who had HIV and babies born SGA had the most blood vessel dysfunction of the four groups.
This study suggests that the placenta’s blood vessels may play an essential role in the connection between women with HIV and their babies born SGA. More research is needed to understand other potential drivers, such as type, timing, and duration of antiretroviral therapies that keep HIV in check and make a healthy pregnancy possible.
Related reading: PrEP: Safe, Effective HIV Prevention Medication for Everyone.
Short- and long-term health impacts of SGA.
In the short term, infants born SGA can face:
- Low blood sugar: Also known as hypoglycemia, this can cause severe symptoms, including seizures.
- Too much bilirubin: Called hyperbilirubinemia, a yellow pigment forms when red blood cells are broken down. This can lead to yellow eyes and skin, jaundice, and liver problems. Left untreated, brain damage can result.
- Respiratory concerns: Having underdeveloped lungs increases the risk of respiratory distress syndrome and bronchopulmonary dysplasia.
- Severe brain injuries: Conditions such as intraventricular hemorrhage or periventricular leukomalacia can lead to significant developmental delays, cerebral palsy, and other neurological problems.
- Eye disorders: Severe retinopathy of prematurity is an eye disorder characterized by the abnormal growth of blood vessels in the retina, which can lead to blindness.
As they grow, SGA babies can face other difficulties, including:
- Short stature: Although many infants catch up in growth, some remain of average height. Quick growth can increase the risk of obesity or metabolic concerns.
- Neurodevelopment: SGA increases the risk of cognitive and learning disabilities, attention problems, and ADHD.
- Cardiometabolic health: SGA is associated with a higher risk of type 2 diabetes, high blood pressure, and heart disease later in life.
- Asthma and other breathing problems: Studies have shown that low birthweight can raise the risk of asthma in childhood.
Related reading: Research Shows Ryan White Program Supports Longer Lives for Patients with Barriers to HIV Care.
Working together to learn more about HIV and SGA.
Our study was the first to demonstrate this connection between the placenta, SGA, and maternal HIV. This research suggests there’s potential for the mechanism behind SGA, and one day, to prevent or reverse it.
We have proposed new research to the National Institutes of Health to develop our study findings further. Our next study will investigate what triggers these placental blood vessels to contract or relax, and whether we can manipulate this signaling process. We hope to learn where these messages originate and whether HIV, antiretroviral therapies, or another explanation, such as inflammation, is behind this dysfunction.
MedStar Health Research Institute is proud to collaborate with our patients on important research like this. Participating in research enables our patients to contribute to science, allowing us to collaborate with them to advance health in our communities.
Working together, we’re on the way to a better understanding of HIV in pregnancy and improving the health and healthcare of women and babies in our communities.
