Women in Sweden, as in many other countries, are giving birth later and later in life. Today the average age of the mother at the birth of the first child is 29, and it is no longer unusual for women over 40 to become mothers. The proportion of women who give birth after the age of 40 has doubled since the early 1980s. It has long been known that the risk of miscarriage increases and that it is more difficult to become pregnant the older the woman is, but our knowledge of how the outcome of pregnancy is influenced by the age of the mother has been scant.
A study from the Section for Obstetrics and Gynecology at the Sahlgrenska Academy in Göteborg has analyzed the results of all pregnancies in Sweden between 1987 and 2001. This represents a total of nearly 1.6 million pregnancies. Complications and the outcome of pregnancies among women aged 40-44 and 45 and older were given special attention and were compared with data for women aged 20-29 giving birth during the same period. The results of the study are published in the October issue of the American journal Obstetrics and Gynecology.
In summary, the extensive study shows that more children born to women between 40 and 44 and 45 and older die in the womb or during the first month of life than children of mothers in their 20s. The results demonstrate that six of 1,000 children born to women in their 20s die in the womb or during the first 28 days. The corresponding number for women between 40 and 44 is eleven, and for women over 45 seventeen.
“But even though the increase in risk is clear, it is still the case that few children die, even if the mother is over 40. All told, it is a matter of a half to one and a half percent of pregnancies that end in this unfortunate way,” says Bo Jacobsson, who led the study.
The pregnant women in their 40s also ran a greater risk of developing complications like high blood pressure, diabetes, blood clots, and other diseases. Women in the 40-44 and 45 and older age groups also present prematurely to a greater extent and more commonly have twins than younger women do.
“This knowledge is vital, since it will provide a basis for how health-care personnel advise couples regarding the importance of the woman’s age in giving birth. The knowledge is also important when it comes to the determining how society should approach postponed reproduction periods,” says Bo Jacobsson.