title: Problems in the long-term assessment of risks from drugs used in pregnancy maintenance.
abstract: Progestogens and oestrogens used to maintain pregnancy in cases of threatened abortion could have side-effects on the mother or fetus. The difficulties in interpreting epidemiological studies on the effects of sex hormones on pregnancy are discussed in relation to the combination of hormones employed, their purpose, time of usage and dosage.
mesh_terms: D004334:Drug Administration Schedule; D004812:Epidemiologic Methods; D004967:Estrogens / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D011247:Pregnancy; D011248:Pregnancy Complications / Q000188:drug therapy*; D011372:Progestins / Q000009:adverse effects*; D012306:Risk
chemical_list: D004967:Estrogens; D011372:Progestins