(Reuters Health) - Pregnant and breastfeeding women who travel to places with high risk of diseases like malaria and yellow fever are less likely than other women travelers to be protected by vaccines and drugs, recent U.S. research suggests.

Lack of information about the safety of some preventive medications and vaccines during pregnancy and breastfeeding may be one reason some patients and doctors avoid them, the study team writes in Obstetrics & Gynecology.

“(There is) a tremendous lack of research in pregnant and breastfeeding women especially related to medication usage and vaccinations,” said Diane L. Spatz of the University of Pennsylvania School of Nursing in Philadelphia, who wasn’t involved in the study.

The research team, Stefan H. F. Hagmann of the Steven and Alexandra Cohen Children’s Medical Center of New York in New Hyde Park and his colleagues, analyzed patient information from Global TravEpiNet, a consortium of U.S. travel clinics that collects data on clinic users planning international travel.

Travel clinics typically specialize in providing advice, immunizations and preventive medications that are needed or recommended for specific foreign destinations.

Other sources, such as the U.S. Centers for Disease Control and Prevention (CDC), also post travel advisories about disease outbreaks and recommend destination-specific measures.

Pregnant women are more susceptible to certain infectious diseases, including malaria and influenza, and in some cases experience more severe symptoms, the study team writes.

Hagmann’s team compared data on 170 pregnant women,139 breastfeeding women and 1,545 non-pregnant/lactating women who received pre-travel care at 24 Global TravEpiNet member clinics between 2009 and 2014.

They found that most pregnant and breastfeeding women intended to travel to tropical destinations where mosquito-borne illnesses such as malaria, dengue, or yellow fever are normally present; and up to one third of pregnant travelers traveled to areas in the Americas, which, since the study was conducted, have experienced chikungunya and Zika virus epidemics.

Most pregnant and breastfeeding women seen during northern hemisphere flu season had been vaccinated against the flu or received a shot during their clinic visit.

Typhoid and hepatitis A were the most commonly administered vaccines to the pregnant and breastfeeding women during clinic visits. Still, these women were about half as likely as nonpregnant, nonbreastfeeding women to get these vaccines during their visit.

Among travelers to countries where malaria is present year-round, about 50 percent of pregnant or breastfeeding women received preventive medications, compared to 73 percent of non-pregnant, non-breastfeeding women.

Despite risky travel destinations, in some cases vaccines and drugs were declined by travelers, or withheld by healthcare practitioners, the study authors note, likely due to limited research on the risks of using certain vaccines, such as those for typhoid and yellow fever, as well as antimicrobial medications, during pregnancy.

“I was not really surprised by any of the study’s findings,” Spatz said. “I am not confident that most women seek specific travel health care before traveling and their primary health care providers may or may not speak to them about these issues.”

Overall, pregnant travelers underused vaccines for typhoid, a potentially life-threatening and increasingly multidrug resistant illness, and hepatitis A, a common infection in poorer countries. Pregnant and breastfeeding travelers also received fewer provisional prescriptions than the comparison group for standby antibiotics to treat diarrhea.

Hagmann did not respond to a request for comments, but the study team acknowledges limitations in its report, notably that the women seen in Global TravEpiNet clinics may not represent all pregnant or breastfeeding women travelers.

There must be increased awareness among providers and travelers of the fact that travel advisories exist, said Dr. Diana E. Ramos of the Keck School of Medicine of the University of Southern California in Los Angeles, who wasn’t involved in the study.

“We need to encourage the public to proactively do research on their risk, and if pregnant, the risk to their fetus, if they travel,” Ramos said in an email.

SOURCE: bit.ly/2zIoEg0 Obstetrics & Gynecology, online November 3, 2017.