Pregnancy in the 20’s
Women in their twenties have a good chance of becoming pregnant as a result of a relatively greater number of eggs in their ovaries. Additionally, a larger percentage of those eggs are normal genetically. Since a woman is born with all of the eggs that they will have in their lifetime, the older she gets the fewer eggs are left. In addition, as women age the percentage of genetically normal eggs remaining decreases. This is why women have a decreasing fertility rate, increased miscarriage rate and increased chance of birth defects like Down syndrome as they age.
The pregnancy rate per month of a woman in her 20’s is about 20-25%. The spontaneous miscarriage rate is only about 5-10% and the incidence of a genetic abnormality like Down syndrome is about 1/1200.
Pregnancy in the early 30’s
Women in their thirties will experience a decline in their fertility such that the fertility rate per month is about 15%. The risk of miscarriage at thirty is about 20%. It is important for all women contemplating pregnancy to start prenatal vitamins at least one month prior to starting to try to become pregnant since there is evidence that extra folic acid prior to pregnancy decrease the incidence of certain types of birth defects. There is also some data suggesting that there is benefit to taking extra omega 3 fatty acid supplements during pregnancy as well.
Pregnancy over Age 35 and Related Risks
A number of different problems characterize the ability to achieve pregnancy over 35. There is a noticeable decline in the fertility rate starting at age 35 to a level of about 10% per month. The pregnancy risk over 35 is higher as well as evidenced an increase in the miscarriage rate and the incidence of genetic abnormality in pregnancy. At 35, the miscarriage rate is 25% and the risk of Down syndrome becomes about 1/350.
Pregnancy over 40 and Related Risks
There is a sharp decline in a woman’s ability to achieve pregnancy over age forty. The fertility rate per month is only about 5% and even with in Vitro Fertilization (IVF), the most successful infertility treatment available, the pregnancy rate is only about 10% per try. This is due to the greatly reduced number of normal eggs remaining in the ovaries of a woman over forty. Estimates from embryo biopsy reveal that at least 90% of a woman’s eggs are genetically abnormal when a woman is over 40. This explains the increased pregnancy risk over 40. The miscarriage rate is 33% at age 40. Genetically abnormal pregnancies are more common as well with an incidence of 1/38 at age 40. As women get older the risks of medical conditions complicating pregnancy increase. Complications of pregnancy that increase with age include elevated blood pressure, gestational diabetes, premature labor and bleeding disorders such as placental abruption.
Pregnancy over 45 and Related Risks
Pregnancy over 45 is a very difficult proposition. Women over 45 have less than a 1% chance of getting pregnant using their own eggs. This is because virtually all of their remaining eggs are genetically abnormal. Successful pregnancy over 45 is therefore nearly always the result of egg donation. Many high profile women who have become pregnant in their forties, especially after the age of 45 did so with the help of donor eggs. The pregnancy risk over 45 is also increased. In the unlikely event that a woman over 45 becomes pregnant with her own eggs, the pregnancy risk over 45 results in a miscarriage rate of at least 50% and the incidence of a genetically abnormal pregnancy of 1 in 12. There is also a significantly higher risk of maternal and fetal mortality with pregnancy over 45 compared to younger women. It is especially important to make sure that a woman’s body is able to tolerate the stresses that pregnancy places on it prior to becoming pregnant. This means that a woman should be checked for problems like high blood pressure, heart disease and diabetes before trying to become pregnant.