Infectious Diseases

29 July 2016

Timing conception might help reduce Zika risk

Instead of women not getting pregnant, the virus might be be avoided if pregnancy is aligned with a time of year when there are fewer mosquitoes around.


Women in Zika-affected countries might reduce their risk of infection during pregnancy by timing conception with periods of low mosquito activity, a new study suggests.

Pinpointing safe time

Zika is the mosquito-borne virus that's been linked to miscarriages and serious birth defects. Since last year, several countries in the Caribbean and in Central and South America have been hit hard by the epidemic, most notably Brazil. Women in many of these countries have been told to avoid pregnancy until a treatment is found.

Read: Doctors urged to check pregnant women for Zika

"Instead of telling women in these countries to not get pregnant, what if we take advantage of the fact that the virus can be avoided if pregnancy is aligned with a time of year when there are fewer mosquitoes?" said study author Micaela Martinez. She is a postdoctoral researcher at Princeton University's department of Ecology and Evolutionary Biology.

"All other animals time their reproduction to match favourable environmental conditions. Why couldn't we?" she said in a university news release. "Mosquitoes are seasonal, which most people are quite aware of, but we tend not to think about that in terms of preventing infections."

Martinez said she created a computer programme that could help local officials, health care workers or scientists pinpoint by calendar week when it's safe for women in their region to conceive.

For the study, the researchers looked at birth data from a number of countries. They estimated that planning conception during seasons with low mosquito activity for as few as three percent of all births could prevent Zika-related birth defects in thousands of babies.

Read: Zika virus: 14 things you need to know

For example, this approach could reduce the risk for about 1,000 births a year in Puerto Rico, and more than 88,000 births a year in Brazil, the study authors said.

Vector control

There is no vaccine or treatment for Zika.

It's likely that planning conception during periods of low mosquito activity would be most effective when used with other Zika prevention measures, especially controlling mosquitoes, according to Alex Perkins, a professor of biological sciences at the University of Notre Dame. He wasn't involved in the research, but is familiar with the findings.

"Vector control is essentially the only tool that we have at the moment to combat Zika virus, and doing so more aggressively at certain times of year – or in certain populations – could interact with modifications of the timing of conception proposed here," Perkins said in the news release.

The researchers said more study of the seasonal patterns of the Zika virus is needed before any policy suggestions can be made.

The study was published in the journal PLoS Biology.

Read more:

Scientists analyse risk to pregnant women infected with Zika

Zika virus: pregnant women shouldn't travel to Brazil

Urine test could simplify Zika virus detection