Editing Trimethoprim (section)

=== Pregnancy ===
Based on the studies that show that trimethoprim crosses the [[placenta]] and can affect folate metabolism, there has been growing evidence of the risk of structural birth defects associated with trimethoprim, especially during the first [[Pregnancy|trimester]] of pregnancy.<ref name="Sivojelezova 1085–1086">{{cite journal | vauthors = Sivojelezova A, Einarson A, Shuhaiber S, Koren G | title = Trimethoprim-sulfonamide combination therapy in early pregnancy | journal = Canadian Family Physician | volume = 49 | pages = 1085–1086 | date = September 2003 | pmid = 14526858 | pmc = 2214286 }}</ref>

The trophoblasts in the early fetus are sensitive to changes in the folate cycle. A 2013 study found a doubling in the risk of miscarriage in women exposed to trimethoprim in the early pregnancy.<ref>{{cite journal | vauthors = Andersen JT, Petersen M, Jimenez-Solem E, Broedbaek K, Andersen EW, Andersen NL, Afzal S, Torp-Pedersen C, Keiding N, Poulsen HE | title = Trimethoprim use in early pregnancy and the risk of miscarriage: a register-based nationwide cohort study | journal = Epidemiology and Infection | volume = 141 | issue = 8 | pages = 1749–1755 | date = August 2013 | pmid = 23010291 | pmc = 9151599 | doi = 10.1017/S0950268812002178 | s2cid = 19917493 }}</ref>