[Medical Q&A] Can birth defects be detected during pregnancy?

Author: Zhao Quming, deputy chief physician, Children's Hospital Affiliated to Fudan University

Reviewer: Huang Guoying, Chief Physician and Professor, Children's Hospital Affiliated to Fudan University

Birth defects refer to abnormalities in the baby's body structure, function or metabolism that occur before birth. They are the main cause of early miscarriage, stillbirth, infant death and congenital disabilities.

Birth defects may occur at any time during pregnancy, and most of them occur in the first 3 months of pregnancy. However, there are many types of birth defects, and the screening methods themselves have certain limitations. Even with regular prenatal examinations, not all birth defects can be detected during pregnancy. The "Guidelines for Ultrasound Prenatal Screening" issued by my country in 2022 pointed out that according to the current level of ultrasound technology, the main serious fetal structural malformations screened at 20 to 24+6 weeks of pregnancy include 9 types, namely anencephaly, alobar holoprosencephaly, severe meningoencephalocele, severe open spina bifida with myelomeningocele, single ventricle, single great artery, bilateral kidney absence, severe chest and abdominal wall defects and visceral eversion, and lethal bone dysplasia with severe short limbs.

Some birth defects, such as clubfoot, cleft lip and palate, or microcephaly, can be seen when the baby is born or easily found through physical examination. But more need to be found through newborn screening, including heel blood screening for genetic metabolic diseases, hearing screening, and congenital heart disease screening.