Final answer:
Exposure to lithium during the first trimester of pregnancy can cause birth defects and developmental abnormalities in the fetus.
Step-by-step explanation:
Exposure to lithium during the first trimester of pregnancy can have harmful effects on the neonate. Lithium is classified as a teratogen, which means it can cause birth defects and developmental abnormalities in the fetus. Some potential effects of lithium exposure in the first trimester include cardiac malformations, central nervous system abnormalities, and growth restriction.