Background
Methods
The Swedish medical birth register
Measures
Variable | Categories |
---|---|
Maternal age | ≤39 years of age, 40–44 years of age, ≥45 years of age |
Civil status | Married/cohabiting, Single |
Employment | Unemployed/student/other, Full time employment, Part time employment |
Maternal BMI | Normal, Underweight, Overweight, Obese |
Tobacco use | No, Yes |
Chronic illness | No, Yes |
ART | No, Yes |
Pre-eclampsia/eclampsia | No, Yes |
Gestational diabetes | No, Yes |
Gestational hypertension | No, Yes |
Premature contractions | No, Yes |
Infection during pregnancy | No, Yes |
Haemmorhage (pre-, intra-, and post-partum) | No, Yes |
Paracervical block | No, Yes |
Pethidine | No, Yes |
Pudendal block | No, Yes |
Epidural | No, Yes |
Mode of delivery | Normal delivery, Elective caesarean, Emergency caesarean, Instrumental delivery |
Gestational age | Very preterm, < 32 weeks, Preterm, 32–36 weeks, At term, 37–42 weeks, Post term, > 42 weeks |
Birthweight | Normal birthweight, > = 2500 g, Low birthweight, 1500-2499 g, Very low birthweight, < 1500 g |
Size for gestational age | Appropriate for gestational age (AGA), Small for gestational age (SGA), Large for gestational age (LGA) |
Apgar, 5 min | 0–6, 7–10 |
Apgar, 10 min | 0–6, 7–10 |
Child’s health at delivery | Healthy – Yes, Healthy – No |
Neonatal survival | 0–27 days, > = 28 days |
Statistical analysis
Ethical approval
Results
Mothers ≤ 39 n = 71,472 | Mothers 40–44 n = 35,329 | Mothers ≥ 45 n = 2229 | P-value1 | P-value2 | P-value3 | P-value4 | ||||
---|---|---|---|---|---|---|---|---|---|---|
min-max (mean/sd) | min-max (mean/sd) | min-max (mean/sd) | ||||||||
Maternal age, min-max (mean/sd) | 14–39 (31.45/4.54) | 40–44 (41.41/1.19) | 45–55 (45.92/1.39) | < 0.001 | < 0.001 | < 0.001 | < 0.001 | |||
n | % | n | % | n | % | P-value1 | P-value2 | P-value3 | P-value4 | |
Civil status | < 0.001 | < 0.001 | < 0.001 | < 0.001 | ||||||
Married/ cohabiting | 64,059 | 89.6 | 30,106 | 85.0 | 1802 | 80.8 | ||||
Single status at registration | 7413 | 10.4 | 5323 | 15.0 | 427 | 19.2 | ||||
Parity | 0.001 | < 0.001 | 0.664 | 0.126 | ||||||
Primiparous | 15,660 | 21.9 | 7417 | 20.9 | 497 | 22.3 | ||||
Multiparous | 55,812 | 78.1 | 28,012 | 79.1 | 1732 | 77.7 | ||||
Worked during pregnancy | < 0.001 | < 0.001 | < 0.001 | 0.004 | ||||||
Unemployed/ student/ other | 17,103 | 27.4 | 6418 | 20.8 | 454 | 23.9 | ||||
Full time | 27,543 | 44.2 | 16,219 | 52.5 | 964 | 50.8 | ||||
Part time | 17,717 | 28.4 | 8267 | 26.8 | 478 | 25.2 | ||||
Tobacco use during pregnancy | < 0.001 | < 0.001 | 0.004 | 0.383 | ||||||
Yes | 8329 | 12.3 | 3588 | 10.8 | 210 | 10.2 | ||||
Mother’s BMI (registration) | < 0.001 | < 0.001 | < 0.001 | 0.003 | ||||||
Normal | 35,306 | 56.2 | 16,156 | 53.2 | 905 | 48.9 | ||||
Underweight | 1165 | 1.9 | 291 | 1.0 | 21 | 1.1 | ||||
Overweight | 17,117 | 27.3 | 9338 | 30.8 | 611 | 33.0 | ||||
Obese | 9185 | 14.6 | 4566 | 15.0 | 314 | 17.0 | ||||
Chronic illnessb | 0.725 | 0.890 | 0.440 | 0.422 | ||||||
Yes | 15,035 | 21.0 | 7440 | 21.0 | 484 | 21.7 | ||||
ART | < 0.001 | < 0.001 | < 0.001 | < 0.001 | ||||||
Yes | 1894 | 2.6 | 2813 | 7.9 | 249 | 11.2 |
Mothers ≤ 39 n = 71,472 | Mothers 40–44 n = 35,429 | Mothers ≥ 45 n = 2229 | p-value1 | p-value2 | p-value3 | p-value4 | ||||
---|---|---|---|---|---|---|---|---|---|---|
n | % | n | % | n | % | |||||
Pre-eclampsia/eclampsia | < 0.001 | < 0.001 | < 0.001 | < 0.001 | ||||||
Yes | 1776 | 2.5 | 1365 | 3.9 | 146 | 6.6 | ||||
Gestational diabetes | < 0.001 | < 0.001 | < 0.001 | < 0.001 | ||||||
Yes | 935 | 1.3 | 917 | 2.6 | 86 | 3.9 | ||||
Gestational hypertension | < 0.001 | < 0.001 | < 0.001 | 0.017 | ||||||
Yes | 679 | 1.0 | 549 | 1.5 | 49 | 1.2 | ||||
Premature contractions | 0.008 | 0.011 | 0.055 | 0.169 | ||||||
Yes | 229 | 0.31 | 82 | 0.2 | 2 | 0.1 | ||||
Infection | 0.966 | 0.815 | 0.925 | 0.873 | ||||||
Yes | 200 | 0.3 | 102 | 0.3 | 6 | 0.3 | ||||
Haemorrhage, prepartum | 0.910 | 0.525 | 0.677 | 0.509 | ||||||
Yes | 25 | 0.0 | 11 | 0.0 | 1 | 0.0 | ||||
Mode of delivery | < 0.001 | < 0.001 | < 0.001 | < 0.001 | ||||||
Caesarean section (elective) | 5328 | 7.5 | 4931 | 13.9 | 455 | 20.4 | ||||
Caesarean section (emergency) | 4931 | 6.9 | 4249 | 12.0 | 370 | 16.6 | ||||
Instrumental deliveryb | 3592 | 5.0 | 2255 | 6.4 | 118 | 5.3 | ||||
Epidural | < 0.001 | < 0.001 | < 0.001 | 0.001 | ||||||
Yes | 14,454 | 20.2 | 6809 | 19.2 | 363 | 16.3 | ||||
Haemorrhage, intrapartum | < 0.001 | < 0.001 | < 0.001 | < 0.001 | ||||||
Yes | 1242 | 1.7 | 1206 | 3.4 | 124 | 5.5 | ||||
Haemorrhage, postpartum | < 0.001 | < 0.001 | < 0.001 | 0.010 | ||||||
Yes | 3013 | 4.2 | 1658 | 4.7 | 131 | 5.9 | ||||
Paracervical block a | 0.571 | 0.296 | 0.803 | 0.973 | ||||||
Yes | 922 | 1.5 | 371 | 1.4 | 20 | 1.4 | ||||
Pethidine a | 0.019 | 0.013 | 0.258 | 0.063 | ||||||
Yes | 1738 | 2.8 | 667 | 2.5 | 47 | 3.3 | ||||
Pudendal block a | < 0.001 | < 0.001 | 0.402 | 0.617 | ||||||
Yes | 1446 | 2.4 | 771 | 2.9 | 38 | 2.7 |
Mothers ≤ 39 n = 71,472 | Mothers 40–45 n = 35,429 | Mothers ≥ 45 n = 2229 | CHI-SQUARE/ANOVA | |||||||
---|---|---|---|---|---|---|---|---|---|---|
mean/SD | mean/SD | mean/SD | p-value1 | p-value2 | p-value3 | p-value4 | ||||
Child’s length, cm (mean/SD) | 50.34/ 2.65 | 50.27/ 2.85 | 49.85/ 3.30 | < 0.001b | < 0.001b | < 0.001b | < 0.001b | |||
Child’s weight, gram (mean/SD) | 3541.49/ 604.21 | 3507.06/ 639.68 | 3403.80/ 706.41 | < 0.001b | < 0.001b | < 0.001b | < 0.001b | |||
n | % | n | % | n | % | p-value1 | p-value2 | p-value3 | p-value4 | |
Twin | < 0.001 | 0.007 | < 0.001 | < 0.001 | ||||||
No | 68,452 | 95.8 | 34,056 | 96.1 | 2033 | 91.2 | ||||
Yes | 3020 | 4.2 | 1373 | 3.9 | 196 | 8.8 | ||||
Gestational age | < 0.001 | < 0.001 | < 0.001 | < 0.001 | ||||||
Very preterm, < 32 weeks | 680 | 1.0 | 436 | 1.2 | 54 | 2.4 | ||||
Preterm, 32–36 weeks | 3870 | 5.4 | 2156 | 6.1 | 187 | 8.4 | ||||
Post term, > 42 weeks | 245 | 0.3 | 127 | 0.4 | 8 | 0.4 | ||||
Birthweight | < 0.001 | < 0.001 | < 0.001 | < 0.001 | ||||||
Low birthweight, 1500 g-2499 g | 2633 | 3.7 | 1558 | 4.4 | 153 | 6.9 | ||||
Very low birthweight, < 1500 g | 534 | 0.7 | 405 | 1.1 | 48 | 2.2 | ||||
Size for gestational age | < 0.001 | < 0.001 | < 0.001 | 0.884 | ||||||
AGA5 | 67,107 | 93.9 | 32,710 | 92.3 | 2052 | 92.1 | ||||
SGA6 | 1281 | 1.8 | 987 | 2.8 | 63 | 2.8 | ||||
LGA7 | 3084 | 4.3 | 1732 | 4.9 | 114 | 5.1 | ||||
Apgar 5 | < 0.001 | < 0.001 | < 0.001 | 0.168 | ||||||
Low score, 0–6 | 763 | 1.1 | 546 | 1.6 | 43 | 1.9 | ||||
Apgar 10 | < 0.001 | < 0.001 | < 0.001 | 0.015 | ||||||
Low score0–6 | 253 | 0.4 | 181 | 0.5 | 20 | 0.9 | ||||
Child healthc | < 0.001 | < 0.001 | < 0.001 | < 0.001 | ||||||
Healthy – No | 14,282 | 20.4 | 8422 | 24.3 | 602 | 27.7 | ||||
Survival | < 0.001 | < 0.001 | 0.011 | 0.328 | ||||||
0–27 days | 123 | 0.2 | 102 | 0.3 | 9 | 0.4 |
ART | Spontaneous | |||||||
---|---|---|---|---|---|---|---|---|
≤39 | 40–44 | ≥45 | p-valueb | ≤39 | 40-44 | ≥45 | p-valueb | |
n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | |||
Civil status | < 0.001 | < 0.001 | ||||||
Married/ cohabiting | 1859 (98.2) | 2651 (94.2) | 227 (91.2) | 62,200 (89.4) | 27,455 (84.2) | 1575 (79.5) | ||
Single status at registration | 35 (1.8) | 162 (5.8) | 22 (8.8) | 7378 (10.6) | 5161 (15.8) | 405 (20.5) | ||
Parity | < 0.001 | |||||||
Primiparous | 872 (46.0) | 1318 (46.9) | 120 (48.2) | 0.754 | 14,788 (21.3) | 6099 (18.7) | 377 (19.0) | |
Multiparous | 1022 (54.0) | 1495 (53.1) | 129 (51.8) | 54,790 (78.7) | 26,517 (81.3) | 1603 (81.0) | ||
Twin | < 0.001 | < 0.001 | ||||||
No | 1404 (74.1) | 2381 (84.6) | 170 (68.3) | 67,048 (96.4) | 31,675 (97.1) | 1863 (94.1) | ||
Yes | 490 (25.9) | 432 (15.4) | 79 (31.7) | 2530 (3.6) | 941 (2.9) | 117 (5.9) | ||
Gestational age | < 0.001 | < 0.001 | ||||||
At term, 37–42 weeks | 1556 (82.2) | 2454 (87.2) | 190 (76.3) | 65,066 (93.6) | 30,223 (92.8) | 1787 (90.4) | ||
Post term, > 42 weeks | 4 (0.2) | 11 (0.4) | 1 (0.4) | 241 (0.3) | 116 (0.4) | 7 (0.4) | ||
Preterm, 32–36 weeks | 277 (14.6) | 284 (10.1) | 49 (19.7) | 3593 (5.2) | 1872 (5.7) | 138 (7.0) | ||
Very preterm, < 32 weeks | 57 (3.0) | 64 (2.3) | 9 (3.6) | 623 (0.9) | 372 (1.1) | 45 (2.3) | ||
Birthweight | < 0.001 | < 0.001 | ||||||
Normal birthweight, ≥2500 g | 1614 (85.5) | 2526 (90.0) | 193 (77.8) | 66,533 (95.8) | 30,834 (94.8) | 1831 (92.6) | ||
Low birthweight, 1500 g-2499 g | 230 (12.2) | 228 (8.1) | 45 (18.1) | 2403 (3.5) | 1330 (4.1) | 108 (5.5) | ||
Very low birthweight, < 1500 g | 44 (2.3) | 52 (1.9) | 10 (4.0) | 490 (0.7) | 1330 (1.1) | 38 (1.9) | ||
Size for gestational age | 0.255 | < 0.001 | ||||||
AGA1 | 1788 (94.4) | 2637 (93.7) | 226 (90.8) | 65,319 (93.9) | 30,073 (92.2) | 1826 (92.2) | ||
SGA2 | 42 (2.2) | 72 (2.6) | 10 (4.0) | 1239 (1.8) | 915 (2.8) | 53 (2.7) | ||
LGA3 | 64 (3.4) | 104 (3.7) | 13 (5.2) | 3020 (4.3) | 1628 (5.0) | 101 (5.1) |
Age group | All age groups | ||||
---|---|---|---|---|---|
≤39 | 40–44 | ≥45 | ≥40 | ||
OR (95% CI) | OR (95% CI) | OR (95% CI) | OR (95% CI) | OR (95% CI) | |
Civil status | |||||
Married/ cohabiting |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Single status at registration | 7.51 (5.35–10.53) | 4.09 (3.46–4.83) | 3.71 (2.28–6.04) | 0.73 (3.24–4.29) | 4.62 (4.02–5.33) |
Parity | |||||
Primiparous |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Multiparous | 0.27 (0.25–0.30) | 0.21 (0.20–0.23) | 0.22 (0.16–0.30) | 0.25 (0.24–0.27) | 0.24 (0.22–0.25) |
Twin | |||||
No |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Yes | 9.85 (8.58–11.30) | 7.50 (6.87–9.20) | 8.02 (5.21–12.35) | 7.94 (7.22–8.72) | 8.91 (8.06–9.82) |
Age group | |||||
≤ 39 | NA | NA | NA | NA |
Reference
|
40–44 | NA | NA | NA | NA | 3.40 (3.57–4.05) |
≥ 45 | NA | NA | NA | NA | 4.72 (4.05–5.50) |
Gestational age | |||||
At term, 37–42 weeks |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Post term, > 42 weeks | 0.63 (0.23–1.72) | 0.92 (0.49–1.75) | 1.65 (0.19–14.31) | 0.90 (0.54–1.50) | 0.86 (0.51–1.44) |
Preterm, 32–36 weeks | 1.37 (1.14–1.65) | 1.20 (1.00–1.43) | 0.95 (0.55–1.66) | 1.26 (1.12–1.43) | 1.26 (1.12–1.43) |
Very preterm, < 32 weeks | 1.57 (0.93–2.64) | 1.92 (1.15–3.19) | 0.13 (0.02–0.93) | 1.47 (1.03–2.10) | 1.60 (1.11–2.29) |
Birthweight | |||||
Normal birthweight, ≥2500 g |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Low birthweight, 1500 g - 2499 g | 1.01 (0.81–1.25) | 0.90 (0.72–1.11) | 1.62 (0.88–2.99) | 1.02 (0.88–1.17) | 0.98 (0.85–1.14) |
Very low birthweight, < 1500 g | 0.81 (0.56–1.45) | 0.59 (0.34–1.02) | 4.82 (0.67–34.83) | 0.82 (0.56–1.20) | 0.70 (0.47–1.04) |
Size for gestational age | |||||
AGA1 |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
SGA2 | 1.35 (0.97–1.88) | 0.84 (0.64–1.10) | 1.54 (0.69–3.42) | 1.16 (0.96–1.42) | 1.02 (0.83–1.24) |
LGA3 | 1.27 (0.98–1.64) | 1.08 (0.88–1.32) | 1.70 (0.92–3.16) | 1.22 (1.05–1.43) | 1.17 (1.00–1.37) |
Birthweighta | Gestational agea | Hypertensionb | Diabetesb | (Pre)eclampsialb | Unhealty childb | Survivalb | |
---|---|---|---|---|---|---|---|
B (95% CI) | B (95% CI) | OR (95% CI) | OR (95% CI) | OR (95% CI) | OR (95% CI) | OR (95% CI) | |
Age when giving birth | |||||||
≤ 39 |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
40–44 | −38.44 (−46.36 - -30.53) | −0.12 (− 0.15 - -0.10) | 1.58 (1.39–1.79) | 1.97 (1.79–2.18) | 1.52 (1.40–1.64) | 1.22 (1.18–1.26) | 1.62 (1.20–2.19) |
≥ 45 | −97.49 (−123.94 - -71.05) | −0.39 (− 0.47 - -0.30) | 2.00 (1.43–2.80) | 2.90 (2.27–3.70) | 2.49 (2.05–3.02) | 1.43 (1.29–1.59) | 2.28 (1.05–4.93) |
Civil status | |||||||
Single status at registration | −85.60 (−99.15 - -72.06) | −0.09 (− 0.14 - -0.05) | 0.72 (0.57–0.92) | 1.03 (0.87–1-22) | 1.02 (0.89–1.16) | 1.13 (1.07–1.20) | 1.32 (0.81–2.12) |
Married/cohabiting |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
ART | |||||||
Yes | −31.26 (−48.89 - -13.63) | −0.20 (−0.26 - -0.14) | 1.12 (0.89–1.42) | 1.11 (0.90–1.37) | 1.53 (1.34–1.75) | 1.46 (1.36–1.56) | 1.63 (0.94–2.82) |
No |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Parity | |||||||
Primiparous |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Multiparous | 158.85 (149.87–167.84) | −0.06 (−0.10 - -0.04) | 0.50 (0.44–0.57) | 1.22 (1.07–1.40) | 0.42 (0.38–0.45) | 0.70 (0.67–0.72) | 1.16 (0.80–1.70) |
Twin | |||||||
No |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Yes | −3.88 (−3.97- -3.80) | −3.09 (−3.15- -3.03) | 1.48 (1.14–1.92) | 1.042 (0.80–1.31) | 4.93 (4.40–5.53) | 4.89 (4.57–5.24) | 8.67 (6.10–12.32) |
Mother’s BMI (registration) | |||||||
Normal |
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Reference
|
Underweight | − 232.52 (− 262.07 - -202.97) | −0.34 (−0.43 - −0.24) | 0.60 (0.28–1.26) | 0.92 (0.49–1.74) | 0.71 (0.47–1.08) | 1.09 (0.96–1.24) | – |
Overweight | 81.97 (73.57–90.37) | 0.03 (−0.02–0.03) | 1.66 (1.44–1.91) | 2.21 (1.94–2.52) | 1.61 (1.48–1.76) | 1.21 (1.17–1.26) | 1.25 (0.90–1.74) |
Obese | 129.14 (118.47–139.80) | -0-11 (− 0.14 - -0.07) | 2.89 (2.49–3.36) | 7.18 (6.37–8.10) | 2.88 (2.62–3.17) | 1.66 (1.59–1.73) | 1.50 (1.02–2.22) |