Women and couples planning to get pregnant may want to delay that pregnancy more than 9 months if there is an ongoing outbreak of the Zika virus in their area of residence, although that measure alone is not powerful enough to make a significant dent in stopping the Zika virus from spreading.

That is according to a new study in which investigators examined epidemiological data from Colombian Zika virus cases to determine if delaying pregnancies – which has been advised by a number of Central and South American health ministries – would be an effective course of action against the disease and its effects on both pregnant mothers and their fetuses (Ann Intern Med. 2016 Jul 26. doi: 10.7326/M16-0919 ).

“We developed a data-driven Zika virus transmission model to evaluate the effect of a mass pregnancy delay strategy in which women of reproductive age avoid pregnancy for the recommended duration, at varying degrees of adherence,” wrote Martial L. Ndeffo-Mbah, PhD , of Yale University in New Haven, Conn., and his coauthors.

Cases included were reported to Colombia’s National Institute of Health between Oct. 11, 2015, and May 8, 2016. Investigators classified cases as “suspected cases” of Zika virus infection if the patient presented to a hospital or clinic with “rash, fever (temperature higher than 37.2 degrees C), and at least one of the following symptoms within 5 days of symptom onset that could not be explained by other medical conditions: nonpurulent conjunctivitis or conjunctival hyperemia, arthralgia, myalgia, headache, or malaise.”

Modeling was used to project incidence rates of Zika virus infections, based on a 50% adherence rate to the recommendations.

Among those women who would delay getting pregnant by 6 months or less after possible exposure to Zika virus, prenatal Zika virus infections would decrease by 2%-7%. However, that number would decrease substantially, by 7%-44%, for those who delayed their pregnancy by as much as 9-24 months after exposure.

“Because the incidence peak of the epidemic occurs around 8 months into the outbreak, a strategy to delay pregnancy by more than 9 months, initiated at the onset of the epidemic, would allow women of reproductive age to avoid being pregnant during the incidence peak, when risk for exposure to Zika virus is highest,” Dr. Ndeffo-Mbah and his coauthors noted.

While delaying pregnancy can significantly reduce the risk of birth defects in infants, the authors noted, it won’t have the same effect on reducing the overall spread of Zika virus in an affected region.

“Our results indicate that delays in pregnancy alone will probably be insufficient to curtail Zika-related birth abnormalities,” the authors concluded. “In the absence of a vaccine or therapeutic drugs for Zika virus infection, a combination of mass and individual pregnancy-delay strategies with effective vector-control measures is needed to curtail the spread and burden of the ongoing outbreak in the Americas.”

The National Institutes of Health funded the study. Dr. Ndeffo-Mbah and his coauthors reported no relevant financial disclosures.