Definitions applied to estimation of absolute risk of primary fetal and infant outcomes
| Outcome | Numerator | Denominator |
| Miscarriage | Number of miscarriages (pregnancy loss prior to 20 weeks gestation) | Total number of pregnancies |
| Early fetal death | Number of pregnancies lost between 20 and 27 weeks gestation | Total number of pregnancies carried to 20 weeks gestation |
| Late fetal death | Number or pregnancies lost at or following 28 weeks gestation | Total number of pregnancies carried to 28 weeks gestation |
| Microcephaly | Number of microcephaly cases | Total number of pregnancies carried to ≥24 weeks gestation, when microcephaly can be assessed by ultrasound in ZIKV-infected mothers,38 we will consider all pregnancies regardless of whether the pregnancy results in a live birth |
ZIKV, Zika virus.