Like most things, age is the biggest risk factor for complications in pregnancy. When the expectant mother is over 35,  the risks associated with overweight, smoking, gestational diabetes and pre-eclampsia also become higher, according to a register-based analysis from the University of Eastern Finland.

Advanced maternal age has been a growing trend over the past few decades. In Finland, the authors note, 20 percent of mothers in 2013 were over 35 years old. Fertility drugs and IVF have made motherhood possible at almost any age and increased popularity of 'egg freezing' is likely to increase the numbers - but there are some risks that increase after the age of 35 and have nothing to do with the embryos themselves.

In her doctoral dissertation, Reeta Lamminpää, MHSc, analyzed nearly 700,000 expectant mothers and their new-born children by combining the data of 1997-2008 available from three national-level registers: the Finnish Medical Birth Register, the Finnish Hospital Discharge Register and the Finnish Register of Congenital Malformations.

The association between age and an additional risk factor on complications during pregnancy and the outcome of childbirth were studied in four risk groups: expectant mothers diagnosed with pre-eclampsia, expectant mothers who smoked, expectant mothers who were overweight and obese, and expectant mothers diagnosed with gestational diabetes. The outcome of childbirth in advanced maternal age was compared to the outcome of younger mothers, i.e. those under 35.

Early recognition of risk groups is vital

In all of the four risk groups, the risks associated with pregnancy and childbirth were higher in advanced maternal age than in younger expectant mothers. The age of over 35 as such was not a significant independent risk factor, but the risks increased when advanced maternal age was combined with an additional risk factor.

In expectant mothers over 35 and diagnosed with pre-eclampsia, pre-term birth and small-for-gestational-age infant were a particular risk. In expectant mothers over 35 and who smoked, low birth weight, pre-term birth, fetal death and small-for-gestational-age infant were more likely than in younger expectant mothers. Furthermore, in expectant mothers over 35 who were overweight or obese and diagnosed with gestational diabetes, pre-term birth, fetal death, large-for-gestational-age infant and pre-eclampsia in particular were more likely. Moreover, overweight was associated with increased risk of cesarean section in advanced maternal age.

The study showed that the above-mentioned four advanced maternal age groups clearly constitute a risk group that should be provided with enhanced guidance within maternity care. Early recognition of the risk groups would make it possible to guide mothers to further treatment at an earlier stage and, consequently, could help reduce the risks of the mother and the foetus alike.

For the majority of expectant mothers over 35, there are no complications in the pregnancy and childbirth; however, earlier research has shown that they are at a higher risk than younger expectant mothers. Advanced maternal age is also associated with more chronic diseases, which also plays a role in the increased risk levels. The association between maternal age and risks and birth outcomes is a topic on which plenty of research has been carried out; however, advanced maternal age in different risk groups has remained a scarcely studied topic.

Published in BMC Pregnancy and Childbirth, BMC Public Health, and Journal of Maternal-Fetal and Neonatal Medicine. Source: University of Eastern Finland