Hello Health Rounds readers! Today we highlight two potentially important studies for women thinking of becoming pregnant. One  points to a possible risk factor for autism. The other found complications linked to discontinuing GLP-1 drugs. We also report on a possible future use for mRNA vaccines: treating snakebites.

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Novo Nordisk's highly anticipated but ultimately unsuccessful Alzheimer's trials were a long shot, but scientists are still asking if GLP-1 drugs should be tested to prevent the disease in people at risk.

Out-of-whack thyroid hormones during pregnancy in mothers with pre-pregnancy thyroid dysfunction may increase the child's risk of autism, researchers say.

While adequately treated chronic thyroid dysfunction did not increase the odds of an autism diagnosis in offspring, ongoing imbalances across multiple trimesters did increase the risk, study leader Idan Menashe of Ben-Gurion University of the Negev in Israel said in a statement.

The study followed more than 51,000 births, including 4,409 in which mothers had abnormal thyroid hormone levels before or during pregnancy, or both.

As long as any existing thyroid dysfunction was adequately controlled, it was not significantly linked to a higher risk for autism spectrum disorder, according to a report in The Journal of Clinical Endocrinology & Metabolism.

And thyroid dysfunction that began in pregnancy did not appear to increase the risk.

However, having thyroid dysfunction before and during pregnancy was associated with more than a two-fold increase in ASD risk, the researchers found.

This was particularly true for women with underactive thyroid glands and resulting low thyroid hormone levels.

The longer the period of hypothyroidism, the higher the ASD risk, with the odds more than tripled when hormone levels were low during all three trimesters of pregnancy.

Too few women in the study had overactive thyroid glands, so the researchers did not analyze that group separately.

Maternal thyroid hormones are essential for the developing brain in the fetus, the authors noted.

“These findings underscore the need for routine monitoring and timely adjustment of therapy to maintain normal thyroid hormone levels throughout pregnancy,” Menashe said.

Stopping GLP-1 weight-loss drugs before pregnancy appears to increase the risk of complications and preterm delivery, a new study found, running counter to guidelines that say women should suspend taking the medicine prior to becoming pregnant.

“Recommendations suggest their discontinuation before pregnancy because there's not enough information about their safety for unborn babies,” study leader Dr. Jacqueline Maya of Mass General Brigham for Children in Boston said in a statement.

Reviewing data on 1,792 pregnancies in overweight or obese individuals, researchers found that women who stopped taking  GLP-1 medications before or early in pregnancy had a 32% higher risk of gaining more weight than recommended and a 30% higher risk of developing diabetes during pregnancy. They also had a 29% higher risk of high blood pressure during pregnancy, and a 34% higher risk of preterm delivery, compared to those who had never taken GLP-1 drugs.

There were no differences in risk of high or low birth weight, birth length, or Cesarean delivery, the researchers reported in JAMA.

An editorial published with the study notes that obesity itself increases the risks of pregnancy complications such as miscarriage, congenital malformations, preterm birth, gestational diabetes, and preeclampsia. By enabling women to begin pregnancy at a lower body mass index, GLP-1 drugs have great potential to reduce these risks, it said.

“Additional studies are needed on the balance of pre-pregnancy benefits of GLP-1s with the risks associated with interrupting them for pregnancy,” study co-author Dr. Camille Powe of Mass General Brigham said in a statement.

“We need to do more research to find ways to help manage weight gain and reduce risks during pregnancy when stopping GLP-1 medications," Powe added.

A separate study in JAMA reports that use of GLP-1 drugs for postpartum weight loss has spiked in recent years.

Among 382,277 pregnancies in Denmark, 1,549 mothers filled a new prescription for a GLP-1 within 182 days after giving birth.

The rate of use rose from less than 5 per 10,000 postpartum women in 2018 to 34 per 10,000 by the second quarter of 2022, and 173 per 10,000 in the second quarter of 2024, according to the report.