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Table 1 Characteristics of the cohort of women who redeemed, and who did not redeem a nitrosatable prescription drug during the first 22 weeks of pregnancy, 1997–2017, Denmark

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

Characteristic Redeemed nitrosatable drug during the first 22 weeks of pregnancy
No
(n = 552,566)
Yes
(n = 100,244)
Age, y, n (%)
 < 19 5706 (1.0) 1266 (1.3)
 19–24 66,476 (12.0) 14,666 (14.6)
 24–29 193,577 (35.0) 34,355 (34.3)
 29–34 189,329 (34.3) 32,348 (32.3)
 > 34 96,972 (17.5) 17,541 (17.5)
 Missing 506 (0.0) 68 (0.0)
Body mass index, kg/m2, n (%)
 < 18 14,607 (2.6) 2336 (2.3)
 18–25 192,003 (34.7) 27,979 (27.9)
 25–30 55,658 (10.1) 10,271 (10.2)
 > 30 29,124 (5.3) 7361 (7.3)
 Missing 261,174 (47.3) 52,297 (52.2)
Parity, n (%)
 Nulliparous 422,921 (76.5) 68,909 (68.7)
 Primiparous 76,403 (13.8) 17,930 (17.9)
 Multiparous 43,918 (7.9) 11,570 (11.5)
 Missing 9324 (1.7) 1835 (1.8)
Smoking during pregnancy, n (%)
 No 401,154 (72.6) 66,726 (66.6)
 Yes 82,775 (15.0) 19,259 (19.2)
 Missing 68,637 (12.4) 14,259 (14.2)
Maternal level of education, n (%)
 Higher education or PhD 58,747 (10.6) 6820 (6.8)
 Middle education 124,762 (22.6) 18,744 (18.7)
 Basic education 37,321 (6.8) 5834 (5.8)
 High School or vocational 213,658 (38.7) 40,075 (40.0)
 Primary school 101,265 (18.3) 26,277 (26.2)
 Unknown 13,584 (2.5) 2171 (2.2)
 Missing 3229 (0.6) 323 (0.3)
Maternal occupation, n (%)
 Owner of business 10,267 (1.9) 1606 (1.6)
 Chief executive or employee with high income 70,443 (12.7) 9270 (9.2)
 Employee with middle income 106,673 (19.3) 16,453 (16.4)
 Employee with low income 153,572 (27.8) 30,148 (30.1)
 Employee unspecified income 81,095 (14.7) 14,403 (14.4)
 Pensioners 2301 (0.4) 1087 (1.1)
 Unemployed 127,184 (23.0) 27,231 (27.2)
 Missing 1031 (0.2) 46 (0.0)
Urbanicity of maternal address at birth, n (%)
 Rural areasa 130,413 (23.6) 26,497 (26.4)
 Provincial townb 143,405 (26.0) 28,956 (28.9)
 Provincial cityc 84,114 (15.2) 13,289 (13.3)
 Suburb of capital 63,944 (11.6) 12,403 (12.4)
 Capital 121,507 (22.0) 18,205 (18.2)
 Missing 9183 (1.7) 894 (0.9)
Household NO3 average concentration (mg/L), n (%)
 ≤ 1 128,213 (23.2) 23,836 (23.8)
 > 1- ≤ 2 170,870 (30.9) 28,624 (28.6)
 > 2- ≤ 5 181,868 (32.9) 33,501 (33.4)
 > 5- ≤ 25 52,634 (9.5) 10,827 (10.8)
 > 25 18,981 (3.4) 3456 (3.4)
  1. a Municipalities in Denmark where the largest town was <10 000 residents
  2. b Municipalities with a town between 10 000-100 000 residents
  3. c Municipalities with town >100 000 residents