Table 6.

Comparison of Association Studies of Nonsteroidal Anti-inflammatory Drug Use and Spontaneous Abortion Risk

Study n (Country)	Median Gestational Age at Entry	Analysis Approach	NSAID		Spontaneous Abortion Definition	Effect Size
			Criteria	n (%)
Nielsen et al 2001 Nielsen et al 2004(6;30) n = 34,018 Spontaneous abortion: 4,268 Controls: 29,750 (Denmark)	Not provided	Logistic regression (adjusted for gestational age)	Prescribed linked to birth registry Prescribed and filled in the 12 weeks before the date of discharge from hospital after loss Any first-trimester use was used for the controls	381 (1.12%)	Hospital discharge codes. Gestational age cutoff not indicated	Weeks before SAB NSAID taken: 1 week* OR = 3.35, 95% CI 0.88, 12.79 2 to 3 weeks OR = 1.50, 95% CI 0.58, 3.86 4 to 6 weeks OR = 1.50, 95% CI 0.91, 2.47 7 and 9 weeks OR = 1.59, 95% CI 0.93, 2.70 10 to 12 weeks OR = 0.58, 95% CI 0.18–1.85
Li et al 2003 (5) n = 1,033 SAB: 162 Controls: 871 (U.S.)	40 days	Cox regression	Interview Prescribed and over-the-counter use since LMP Ibuprofen, naproxen, Advil, Motrin, Naprosyn	53 (5%)	Before 20 weeks of gestation	Any NSAID use HR = 1.8, 95% CI 1.0, 3.2 NSAID use at conception HR = 5.6, 95% CI 2.3, 13.7 NSAID use after conception HR = 1.2, 95% CI 0.5, 2.6
Nakhai-Pour et al 2011 (7) n = 51,755 Spontaneous abortion: 4,705 Controls: 47,050 (Canada)	Not provided	Logistic regression	Prescribed linked to pregnancy registry Use between index date (gestational age of loss or for controls the gestational age of loss in matched cases) and start of pregnancy Non-aspirin NSAID excluding misoprostol, NSAID suppositories or known teratogens.	1,565 (3%)	Before 20 weeks of gestation	Any NSAID use OR = 2.43, 95% CI 2.12, 2.79
Right from the Start n = 2,780 Spontaneous abortion: 376 Controls: 2,404 (U.S.)	42 days	Cox regression	Interview Over-the-counter Use between LMP and 6 weeks Any type of NSAID	1,595 (43%)	20 weeks of gestation or before	Any NSAID use aHR = 1.01, 95% CI 0. 82, 1.24

NSAID, nonsteroidal anti-inflammatory drug; OR, odds ratio; CI, confidence interval; LMP, last menstrual period.

^*The original dataset from Nielsen et al 2001 was reanalyzed by the authors in order to show the results of their study accounting for the length of time before spontaneous abortion when NSAIDs were used. Results presented are for the reanalysis in Nielsen et al 2004.