Zika, Malaria, and Pregnant Women in Clinical Trials

We recently published a post exploring the need for increased diversity among participants in clinical trials. In that post, we cited certain demographics, including African Americans, the elderly, and more, as some of the most underrepresented in clinical settings. But there is one demographic that we didn’t mention, one whose frequent exclusion from clinical trials could have significant implications for some of today’s biggest global health concerns: pregnant women.

The exclusion of pregnant women from clinical trials originates in a concern for the health and safety of the fetus1. This concern may be particularly acute in Phase I trials, when there is little to no data on how a treatment affects humans. If a pregnant woman enrolls in a study of a treatment that is later deemed unsafe, then both she and her unborn child are at risk of that treatment’s adverse effect. Many researchers prefer to simply decline to recruit pregnant women, resulting in drugs being brought to market with little to no data on how those women will be affected.

Current events lead to calls for change

But this practice has come under scrutiny at a time when some of the major infectious diseases affecting the developing world have a more damaging effect on pregnant women and their babies than on other patients. The Zika virus, for example, which is currently spreading through Latin America, has an apparent link to microcephaly, a condition that causes limited cranial and brain development in newborns. Thousands of cases of microcephaly in children born to women with Zika have been reported, causing some Latin American governments to call for complete abstinence in order to avoid pregnancy altogether until the virus is under control2. And malaria, which last year killed half a million people in Africa, can lead to miscarriage, stillbirth, and low birth weight if left untreated in pregnant women, who meanwhile have been completely excluded from clinical trials for the recommended treatment for the disease3. This is not simply a question of the risk of overlooking a minor demographic-specific side effect; we’re dealing with major symptoms of dangerous diseases exclusively affecting a group that is often ignored in the process of developing treatment for those diseases.

There is, however, an opportunity for change on the horizon. This past January, the National Institute of Allergy and Infectious Diseases announced its interest in funding Zika research. That research would include the development and testing of diagnostic tests, treatments, vaccinations, and more4. If and when the research community answers this call, the resulting surge in new studies may constitute a moment of reckoning, and researchers may finally have to reconcile their safety concerns with the imperative to involve pregnant women–perhaps the most consequential subset of the population affected by Zika–in the clinical trials that target it.

The exclusion of pregnant women from clinical trials can result in a dearth of safe, available treatment for those women. But with prominent infectious diseases like malaria and Zika arguably affecting pregnant women more than anyone else, more and more voices in the medical community are calling for an end to this state of affairs.


1. Faulkes, Mary A., Grady, Christine, Spong, Catherine Y., Bates, Angela, Clayton, Janine A.; Clinical Research Enrolling Pregnant Women: A Workshop Summary; Journal of Women’s Health; 10/20/2011
2 Partlow, Joshua; As Zika virus spreads, El Salvador asks women not to get pregnant until 2018; The Washington Post; 1/22/2016
3 Brink, Susan; Studies Reinforce The Urgency Of Treating Pregnant Women With Malaria; KUOW.ORG; 3/9/2016
4 National Institute of Allergy and Infections Diseases; niaid.nih.gov