A population-based register linkage study examined the association between maternal age and fetal loss, including spontaneous abortion, ectopic pregnancy, and stillbirth. The study included 634,272 women and 1,221,546 pregnancies in Denmark from 1978 to 1992. The results showed that the risk of fetal loss increased with maternal age, with over half of pregnancies at age 42 resulting in fetal loss. The risk of spontaneous abortion was 8.9% in women aged 20-24 and 74.7% in those aged 45 or older. High maternal age was a significant risk factor for spontaneous abortion, regardless of previous miscarriages, parity, or calendar period. The risk of ectopic pregnancy and stillbirth also increased with maternal age. The study concluded that fetal loss is high in women in their late 30s or older, regardless of reproductive history. This should be considered in pregnancy planning and counseling. The study used Danish health registries to control for confounding factors. The risk of fetal loss was 13.5% overall, with a J-shaped curve showing increased risk after 35 years of age. Spontaneous abortion accounted for 80% of fetal losses, with the risk increasing significantly with maternal age. The risk of stillbirth also increased with maternal age, though less than for spontaneous abortion and ectopic pregnancy. The study found that the association between maternal age and fetal loss was not confounded by calendar period or maternal birth cohort. The study highlights the importance of considering maternal age in reproductive decisions and counseling. The study was approved by the Danish Data Protection Board.A population-based register linkage study examined the association between maternal age and fetal loss, including spontaneous abortion, ectopic pregnancy, and stillbirth. The study included 634,272 women and 1,221,546 pregnancies in Denmark from 1978 to 1992. The results showed that the risk of fetal loss increased with maternal age, with over half of pregnancies at age 42 resulting in fetal loss. The risk of spontaneous abortion was 8.9% in women aged 20-24 and 74.7% in those aged 45 or older. High maternal age was a significant risk factor for spontaneous abortion, regardless of previous miscarriages, parity, or calendar period. The risk of ectopic pregnancy and stillbirth also increased with maternal age. The study concluded that fetal loss is high in women in their late 30s or older, regardless of reproductive history. This should be considered in pregnancy planning and counseling. The study used Danish health registries to control for confounding factors. The risk of fetal loss was 13.5% overall, with a J-shaped curve showing increased risk after 35 years of age. Spontaneous abortion accounted for 80% of fetal losses, with the risk increasing significantly with maternal age. The risk of stillbirth also increased with maternal age, though less than for spontaneous abortion and ectopic pregnancy. The study found that the association between maternal age and fetal loss was not confounded by calendar period or maternal birth cohort. The study highlights the importance of considering maternal age in reproductive decisions and counseling. The study was approved by the Danish Data Protection Board.