Protein made in the fetus that normally leaks, in small amounts, into the mother’s circulation.
Note: If there is an abnormal opening in the fetus, such as a
neural tube defect, larger amounts appear in the mother’s serum, providing a screening test for such fetal anomalies.
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 775 (https://doi.org/10.1515/pac-2015-1202)