The Problem of Confounding in Studies of the Effect of Maternal Drug Use on Pregnancy Outcome

Table 3

Use of drugs in early pregnancy among women with a previous relatively severely malformed infant compared with women who had no known previous such malformed infant. Odds ratio (OR) with 95% confidence interval (95% CI) adjusted for year of delivery, maternal age, parity, smoking in early pregnancy, and BMI.

Drug group	Among women with previous malformed infant	Among all women	OR	95% CI
Any drug	2078	290480	1.14	1.08–1.21
Drugs for stomach ulcer and reflux	53	6062	1.17	0.89–1.55
Insulin	43	2614	2.46	2.81–3.32
Multivitamins	218	56200	0.99	0.86–1.15
Folic acid	276	43780	1.26	1.12–1.43
Antihypertensives	35	3147	1.39	0.99–1.94
Thyroid drugs	104	10728	1.31	1.07–1.59
Antibiotics	186	19036	1.04	0.89–1.20
NSAID	127	13047	1.27	1.06–1.52
Opioids	38	3974	1.18	0.85–1.63
Minor analgesics	449	51043	0.96	0.87–1.06
Anticonvulsants	20	2037	1.44	0.92–2.26
Antipsychotics	26	1992	1.53	1.03–2.39
Sedatives/hypnotics	32	3301	1.21	0.91–1.83
Antidepressants	95	11714	1.26	1.02–1.55
Any psychopharmacon	137	15558	1.29	1.08–1.53
Drugs for rhinitis	67	9944	0.86	0.68–1.10
Antiasthmatic drugs	180	22702	1.07	0.92–1.25
Antihistamines	300	38689	0.98	0.87–1.10