ZIKAlliance Pregnant Women Cohort

The aim of this proposal is to evaluate the causal relationship between Zika virus (ZIKV) infections in pregnancy and congenital malformations. We will estimate the absolute and relative risks of congenital malformations and other adverse outcomes of pregnancy among women who become infected with ZIKV during pregnancy compared to uninfected pregnant women, also leading to further validation of the Congenital Zika Syndrome.

We will also determine the ZIKV maternal to child transmission rate and evaluate co-factors or effect modifiers that account for the large variability seen in the preliminary absolute risk estimates derived from population figures and reporting of microcephaly in different states in Brazil and across Latin America.

We will carry out a pregnant women (PW) multicentre cohort study in areas across Latin America and the Caribbean. Women will be enrolled early in pregnancy and followed every 4 weeks, in connection with their routine antenatal care visits. At each visit, urine and blood samples will be collected, tested and stored.

Among PW reporting recent or current undifferentiated fever/rash syndrome at any point in time, the acute illness episode will be characterized in greater detail. PW with suspected ZIKV infection (i.e. meeting the Pan American Health Organization (PAHO) clinical case definition) during pregnancy will be managed according to national protocols. Irrespective of symptoms, pregnant women will be followed prospectively and revisited at birth (or after abortion) for a detailed documentation of the outcome of their pregnancy.

Live newborns will receive a detailed neonatal examination. In the course of examination of the newborns, biological samples will be collected and stored. Other potential causes of congenital abnormalities (TORCHS infections in the mother, toxic substances, chromosomal abnormalities), and potential effect modifiers (for example past flavivirus infections/vaccinations, socio-economic status) will also be assessed.

With appropriate counselling and consent, biological samples of newborns with severe abnormalities, deceased newborns, stillborn babies, and aborted foetuses from ZIKV-infected mothers will be collected to help elucidate the aetiological contribution of ZIKV in neurological and other congenital malformations.

Children of women infected with ZIKV during pregnancy - and a subset of the children born to uninfected women - will be followed prospectively after birth for the assessment of neuro-developmental milestones (separate protocol).

Inclusion criteria

• at least 16 years old
• Pregnancy status confirmed
• Within first or second trimester or first month of marked transmission season

Exclusion criteria

• Planing to leave area
• Unable to attend follow-up visits
• Unable to undergo venipuncture
• Participates in another pregnant women study for ZIKA
• Unable to consent without legal guardian