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Table 4 Hazard ratios (HRs) for stillbirth given prescriptions with secondary amine(s), tertiary amine(s) or amide(s) during the first 22 weeks of pregnancy by levels of maternal household drinking water nitrate concentration

From: Prenatal nitrosatable prescription drug intake, drinking water nitrate, and the risk of stillbirth: a register- and population-based cohort of Danish pregnancies, 1997–2017

Household NO3- average (mg/L) Secondary amine intake during the first 22 weeks of pregnancy No stillbirth Stillbirth HR (95% CI)
Unadjusted Adjusteda
≤1 No 146,486 594 1 1
Yes 4947 22 1.12 (0.74–1.72) 1.22 (0.64–2.30)
> 1- ≤ 2 No 192,737 682 1 1
Yes 6044 31 1.50 (1.05–2.15) 1.39 (0.78–2.49)
> 2- ≤ 5 No 207,954 723 1 1
Yes 6666 26 1.16 (0.78–1.72) 1.20 (0.65–2.20)
> 5- ≤ 25 No 61,126 234 1 1
Yes 2095 6 0.78 (0.35–1.76) 0.38 (0.05–2.76)
> 25 No 21,700 87 1 1
Yes 644 6 2.36 (1.03–5.40) 3.11 (1.08–8.94)
Household NO3- average (mg/L) Tertiary amine intake during the first 22 weeks of pregnancy No stillbirth Stillbirth HR (95% CI)
Unadjusted Adjusteda
≤1 No 141,881 583 1 1
Yes 9552 33 0.85 (0.60–1.21) 0.55 (0.27–1.12)
> 1- ≤ 2 No 187,809 668 1 1
Yes 10,972 45 1.18 (0.87–1.59) 1.79 (1.18–2.69)
> 2- ≤ 5 No 201,622 700 1 1
Yes 12,998 49 1.11 (0.83–1.49) 1.34 (0.85–2.12)
> 5- ≤ 25 No 58,941 221 1 1
Yes 4280 19 1.21 (0.76–1.94) 1.61 (0.74–3.53)
> 25 No 20,950 87 1 1
Yes 1394 6 1.07 (0.47–2.44) 1.54 (0.54–4.35)
Household NO3- average (mg/L) Amide intake during the first 22 weeks of pregnancy No stillbirth Stillbirth HR (95% CI)
Unadjusted Adjusteda
≤1 No 134,846 550 1 1
Yes 16,587 66 0.98 (0.76–1.27) 0.79 (0.50–1.27)
> 1- ≤ 2 No 178,988 622 1 1
Yes 19,793 91 1.34 (1.08–1.67) 1.45 (1.02–2.06)
> 2- ≤ 5 No 191,278 668 1 1
Yes 23,342 81 1.01 (0.80–1.27) 1.07 (0.72–1.59)
> 5- ≤ 25 No 55,633 202 1 1
Yes 7588 38 1.40 (0.99–1.98) 1.50 (0.79–2.86)
> 25 No 19,854 83 1 1
Yes 2490 10 0.98 (0.51–1.90) 0.90 (0.32–2.54)
  1. aAdjusted for parity, urbanicity and maternal age, body mass index, smoking, education and occupation