Increasing access to contraception has the potential to significantly reduce the incidence of microcephaly caused by the Zika virus (ZIKV), according to research recently published in Maternal and Child Health Journal. The Monte Carlo simulation study found that reductions in ZIKV-related microcephaly were greater with enhanced contraceptive access than with an anti-ZIKV vaccine, presuming a conservative scenario with a 10% vaccination uptake.
In-utero exposure to ZIKV can lead to serious brain anomalies, including microcephaly. The study investigators noted that while strategies such as vaccine development, vector control, and encouragement of condom use to prevent sexual transmission have been proposed for averting ZIKV-related microcephaly, scant attention has been paid to the role that could be played by enhanced contraceptive access and the prevention of unintended pregnancy. Almost half (45%) of all pregnancies in the United States are unintended at the time of conception.
In order to determine how many ZIKV-related cases of microcephaly could be avoided by preventing unintended pregnancies, the investigators estimated the number of women of childbearing age expected to be exposed to ZIKV; the number of women in whom ZIKV infection would be prevented in conservative (10%), moderate (50%), and optimistic (90%) anti-ZIKV vaccine uptake scenarios; the number of pregnancies and births expected to occur and the percentage of those pregnancies and births that would be prevented with enhanced contraceptive access; and finally, the expected number of ZIKV-related microcephaly births. Model inputs for effectiveness of enhanced contraceptive access, ZIKV cumulative incidence, ZIKV-related microcephaly risk, and anti-ZIKV vaccination parameters were determined based on the literature or best available knowledge.
Results produced by Monte Carlo sampling techniques (n = 100,000 simulations) showed that the median number of ZIKV-related microcephaly births dropped by 16% with enhanced contraceptive access alone. Conservative, moderate, and optimistic vaccination scenarios resulted in reductions in ZIKV-related microcephaly births of 9% (95% SI: 0, 18), 45% (95% SI: 36, 54), and 81% (95% SI: 71, 91) respectively. A 54% reduction in ZIKV-related microcephaly births (95% SI: 44, 62) was seen with use of both enhanced contraception and vaccination in a moderate uptake scenario.
When asked via email about the clinical implications of the study for infectious disease specialists, lead investigator Katherine A. Ahrens PhD, an epidemiologist with the Department of Health and Human Services’ Office of Population Affairs (OPA), told Infectious Disease Advisor that the study did not evaluate the effects of changes in clinical practice on ZIKV-related birth defects. However, she noted that numerous prior studies have examined the role of contraception in reducing morbidity and mortality, and that enhanced contraception access has been proposed as a strategy for counteracting adverse pregnancy outcomes in non-ZIKV scenarios. “CDC and OPA published clinical recommendations in 2014, titled “Providing Quality Family Planning Services” (QFP), which is designed to “help women, men and couples achieve their desired number and spacing of children, and increase the likelihood that those children are born healthy,” she stated. “QFP recommends screening all women and men of reproductive age for their pregnancy intention and then offering contraception to those that are seeking to prevent or delay pregnancy.”
Ahrens KA, Hutcheon JA, Gavin L, Moskosky S. Reducing unintended pregnancies as a strategy to avert Zika-related microcephaly births in the United States: a simulation study [published online January 19, 2017]. Matern Child Health J. doi:10.1007/s10995-017-2275-2