WEDNESDAY, March 27, 2019 (HealthDay News) -- The risk for miscarriage varies greatly with maternal age, has a strong recurrence pattern, and is increased after some adverse pregnancy outcomes, according to a study published online March 20 in The BMJ.
Maria C. Magnus, Ph.D., from the Norwegian Institute of Public Health in Oslo, and colleagues used the Medical Birth Register of Norway, the Norwegian Patient Register, and the induced abortion register to assess the burden of miscarriage among all Norwegian women who were pregnant between 2009 and 2013 and to evaluate the associations between miscarriage and both maternal age and pregnancy history.
There were 421,201 pregnancies during the study period. The researchers found that women aged 25 to 29 years had the lowest miscarriage risk (10 percent), which rose rapidly after age 30 years and reached 53 percent in women aged 45 years and older. There was a strong risk for recurrent miscarriage, with age-adjusted odds ratios (ORs) of 1.54, 2.21, and 3.97 after one miscarriage, two miscarriages, and three consecutive miscarriages, respectively. There was also a modestly increased risk for miscarriage with adverse outcomes from a previous pregnancy: if the previous birth ended in a preterm delivery (adjusted OR, 1.22), stillbirth (adjusted OR, 1.3), or cesarean section (adjusted OR, 1.16) or if the woman had gestational diabetes (adjusted OR, 1.19).
"More focused studies of these associations might lead to new insights regarding the shared underlying causes of pregnancy complications and miscarriage," the authors write.