Central nervous system abnormalities--contrasting patterns in early and late pregnancy

Area of Science:

• Medical Science
• Developmental Biology
• Genetics

Background:

• Spontaneous abortion is a significant pregnancy complication.
• Central nervous system (CNS) defects are among the most common congenital abnormalities.
• Understanding the incidence and types of CNS defects in early spontaneous abortions is crucial for prenatal diagnosis and prevention strategies.

Purpose of the Study:

• To investigate the prevalence and characteristics of central nervous system (CNS) abnormalities in spontaneously aborted fetuses.
• To compare the incidence of CNS defects in early pregnancy loss with that observed at birth.
• To identify potential risk factors and recommend further screening for subsequent pregnancies.

Main Methods:

• Examination of 509 specimens of spontaneous abortion.
• Detailed analysis of 364 complete specimens, including gross and histological examination.
• Sex chromatin studies and calculation of conception month.

Main Results:

• 15 out of 364 complete specimens (4.1%) exhibited CNS abnormalities, including anencephaly, spina bifida, iniencephaly, and encephalocele.
• Unusual defects like iniencephaly and encephalocele were noted in a significant proportion (5/15).
• Most affected fetuses (all but one) ceased development before 12 weeks of gestation; males outnumbered females among affected fetuses.

Conclusions:

• The incidence of CNS abnormalities in spontaneous abortion is higher than previously reported and significantly higher than at birth.
• Internal CNS abnormalities can be more extensive than external defects, and some fetuses without visible defects also have internal CNS issues.
• Screening for serum alphafetoprotein and considering amniocentesis are recommended for pregnancies following an abortion with CNS defects.