Risk factors (%) registered in Medical Birth Registry of Norway 1972–95 among deliveries of singleton live born infants with birthweights ⩾2500 g
| Congenital malformations* | 2.2 |
|---|---|
| Breech presentation | 2.7 |
| Transverse position | 0.1 |
| Placenta previa | 0.2 |
| Maternal age less than 18 years or more than 40 years | 2.1 |
| Maternal disease before pregnancy† | 14.8 |
| Maternal disease during pregnancy‡ | 18.2 |
| Four previous births or more | 2.0 |
| Gestational age of more than 42 weeks | 13.1 |
| Hydramnios or oligohydramnios | 1.0 |
| Premature rupture of membranes | 0.4 |
| Low risk deliveries§ | 56.4 |
| Total number of infants | 1 260 777 |
The percentages total more than 100% as some deliveries have more than one risk factor.
1-150 All congenital anomalies except congenital dysplasia of the hips.
1-151 All reported maternal diseases before the start of pregnancy, except congenital dysplasia of the hips, allergic diseases, and urinary tract infections.
1-152 All reported maternal diseases with origin during the pregnancy potentially detectable before delivery, also including Rhesus immunisation.
1-153 Women aged 18 to 40 years, with no more than three previous births and no reported diseases before or during a singleton pregnancy, giving births within 42 weeks gestational age to an infant without any congenital anomalies and with a birthweight of 2500 g or more. There were no breech or transverse position, no prolonged ruptures of the membranes, and no hydramnios or oligohydramnios.