Overall, women who are treated with fluoxetine during the first trimester of pregnancy do not appear to have an increased risk of major fetal malformations.
Their use in the first trimester is also associated with a risk of major congenital malformations, particularly affecting the cardiovascular and central nervous systems.
Due to the fact that it crosses the placenta and can affect folate metabolism, trimethoprim is relatively contraindicated during pregnancy, especially the first trimester.
After the first trimester, the woman's body temperature drops to her pre-ovulatory normal as the placenta takes over functions previously performed by the corpus luteum.