What these numbers show

• The number of completed pregnancies with or without birth defects include those that ended in a live birth, miscarriage, stillbirth, or termination.
• The number of liveborn infants and pregnancy losses with birth defects include those among completed pregnancies with laboratory evidence of possible Zika virus infection.
• The numbers are aggregated into two categories 1) the 50 US states and the District of Columbia, and 2) the US territories and freely associated states. At this time, CDC is not reporting individual state, tribal, territorial or jurisdictional data to protect the privacy of the women and children affected by Zika. CDC is using the standard CDC surveillance case definition for the Zika Pregnancy and Infant registries to monitor brain abnormalities, microcephaly, and other serious birth defects that have been linked to Zika virus infection during pregnancy across the United States and territories.
• The numbers may increase or decrease as new cases are added or information on existing cases is clarified.
• Birth defects reported include those that have been linked to Zika virus infection during pregnancy, including microcephaly, calcium deposits in the brain indicating possible brain damage, excess fluid in the brain cavities and surrounding the brain, absent or poorly formed brain structures, abnormal eye development, or other problems resulting from damage to brain that affects nerves, muscles and bones, such as clubfoot or inflexible joints, and confirmed hearing loss.

What these new numbers do not show

• These numbers reflect the outcomes of pregnancies with any laboratory evidence of possible Zika virus infection reported to the Zika pregnancy and infant registries as of the date specified. There may be delays in reporting of pregnancy outcomes from the jurisdictions.
• Although these birth defects occurred from pregnancies of women with laboratory evidence of possible Zika virus infection, we cannot determine whether individual defects were caused by Zika virus infection or other factors.

Where do these numbers come from?

• These data reflect pregnancies reported to the Zika pregnancy and infant registries(https://www.cdc.gov/zika/reporting/index.html). Together, these registries cover the full United States including territories and freely associated states.
• These systems were established in collaboration with state, local, tribal and territorial health departments for comprehensive monitoring of pregnancy and infant outcomes of pregnancies with any laboratory evidence of possible Zika virus infection.
• The data collected through the Zika pregnancy and infant registries will be used to update recommendations for clinical care, to plan for services and support for pregnant women and families affected by Zika virus, and to improve prevention of Zika virus infection during pregnancy.
• The Zika Pregnancy and Infant Registries) are protected by an Assurance of Confidentiality(https://www.cdc.gov/od/science/integrity/confidentiality/index.htm). Under the Assurance, CDC cannot report jurisdiction-specific information without permission from the jurisdiction.

The following details the inclusion criteria for brain abnormalities and other adverse outcomes potentially related to Zika virus infection during pregnancy. All pregnancy outcomes are monitored, but reporting of adverse outcomes is limited to those meeting the criteria below.

Brain abnormalities with and without microcephaly

• Confirmed or possible congenital microcephaly#
• Intracranial calcifications
• Cerebral atrophy
• Abnormal cortical formation (e.g., polymicrogyria, lissencephaly, pachygyria, schizencephaly, gray matter heterotopia)
• Corpus callosum abnormalities
• Cerebellar abnormalities
• Porencephaly
• Hydranencephaly
• Ventriculomegaly / hydrocephaly (excluding “mild” ventriculomegaly without other brain abnormalities)
• Fetal brain disruption sequence (collapsed skull, overlapping sutures, prominent occipital bone, scalp rugae)
• Other major brain abnormalities, including intraventricular hemorrhage in utero (excluding post-natal IVH)

Neural tube defects and other early brain malformations

• Neural tube defects (NTD)
  • Anencephaly / Acrania
  • Encephalocele
  • Spina bifida
• Holoprosencephaly / Arhinencephaly

Structural eye abnormalities

• Microphthalmia / Anophthalmia
• Coloboma
• Cataract
• Intraocular calcifications
• Chorioretinal anomalies involving the macula (e.g., chorioretinal atrophy and scarring, macular pallor, gross pigmentary mottling and retinal hemorrhage); excluding retinopathy of prematurity
• Optic nerve atrophy, pallor, and other optic nerve abnormalities

Consequences of central nervous system (CNS) dysfunction

• Congenital contractures (e.g., arthrogryposis, club foot, congenital hip dysplasia) with associated brain abnormalities
• Congenital deafness documented by postnatal testing

#Live births: measured head circumference (HC) adjusted for gestational age and sex <3rd percentile at birth, or if not measured at birth, within first 2 weeks of life; pregnancy loss: prenatal HC more than 3 standard deviations below the mean based on ultrasound or postnatal HC <3rd percentile. Birth measurements based on intergrowth21 standards which are based on measurements within 24 hours of birth, and therefore measurements within 24 hours of birth are appropriate for this assessment.