Table 5.

Risk of miscarriage in Norway between 2009 and 2013 according to the women’s own birth record (n=258 954*)

Exposure	Total number of pregnancies excluding induced abortions	Number of miscarriages (%)	Adjusted† odds ratio (95% CI)
Gestational age at delivery:
Preterm	10 599	1396 (13.2)	1.05 (0.99 to 1.12)
Term	194 910	24 462 (12.6)	Ref
Post-term	38 044	4955 (13.0)	1.04 (1.00 to 1.08)
Fetal growth:
Small for gestational age	26 397	3598 (13.6)	1.08 (1.04 to 1.13)
Normal for gestational age	195 358	24 571 (12.6)	Ref
Large for gestational age	21 548	2618 (12.2)	0.97 (0.93 to 1.02)
Pre-eclampsia:
No	252 346	31 951 (12.7)	Ref
Yes	6608	852 (12.9)	1.06 (0.98 to 1.15)

^*76 903 pregnancies excluded because they resulted in an induced abortion; 1412 pregnancies excluded because the woman was born before the medical birth register was set up (1967); and 83 932 pregnancies excluded because the woman was born outside of Norway.

^†Adjusted for age.