Trying to get pregnant after 40: why is it more difficult?

More and more women are looking for a child after the age of 40. We will not dwell here on the motivations, but we will try to deepen the consequences of a research, which we can define as late from a biological point of view.

The average age of the first pregnancy in Italy in 2017 was around 32 years of age but the tendency to postpone parenthood has been continuously increasing for several years.

Unfortunately, the biological age of women’s ovaries is not moving forward in parallel, it continues to remain the same, with the consequence that the search for the first child often ends when the woman’s fertility begins to decline, or is already very low. .

After 40 it is more difficult to get pregnant

Fertility decreases with a woman’s age . This is a fact. We currently have no valid tools to counteract this decline, other than preventing the problem by having children earlier (but this is not always possible) or by preserving fertility, through cryopreservation of oocytes.

Unfortunately, over the years, especially after the age of 35, the oocytes gradually decrease in number and quality and, in parallel, the rates of spontaneous abortions increase.

At the age of 44-45 the chances of a spontaneous pregnancy approach zero.

These data are really difficult to accept for those seeking a pregnancy after the age of 40. Unfortunately not even assisted fertilization can work miracles when the fertility problem is linked to the woman’s age.

According to a 2016 report from the CDC , one IVF cycle has a 36% chance of leading to pregnancy in a woman under the age of 35. This probability decreases to 22% between the ages of 38 and 40, and reaches 13% for women aged 41 or 42. The probability reaches 6% when the age exceeds 42 and then drops to zero around 44-45 years. In that case, the alternative is represented by heterologous fertilization (egg donation when the woman’s ovarian reserve does not allow homologous fertilization).

After the age of 40 it is more difficult to continue the pregnancy

Miscarriages and stillbirths can occur at any age, but the chances increase with age. Miscarriages that occur within 20 weeks of pregnancy are almost always caused by chromosomal problems in the embryo, defects that are more likely in older oocytes. For this reason, women between the ages of 40 and 44 have a 33% chance of miscarriage. In practice, they have a one in 3 chance of miscarrying once pregnancy is discovered (compared to a chance of about 1 in 5 in younger women).

Available data also suggest that pregnant women aged 40 or older have a higher risk of stillbirth. The reasons are not clear although according to a 2008 review it is thought that high blood pressure during pregnancy or gestational diabetes, conditions that are more frequent during the pregnancies of older women, may play a role .

Because pregnancies that continue beyond 40 weeks can increase the risk of stillbirth , many doctors do not allow a woman over 40 to go into labor after term but prefer to proceed with a scheduled induction before due date. .

After the age of 40, the risk of complications increases

With age, the chances of developing certain cardiovascular problems such as high blood pressure and certain heart diseases increase. This is one reason why women over the age of 40 are at increased risk of preeclampsia (high blood pressure and protein in the urine during pregnancy, which can be life-threatening) and gestational diabetes. These conditions can create a variety of problems for both mother and baby, including the baby’s low birth weight (or abnormally high birth weight) and premature birth.

Another big problem is an increased chance of developing a condition known as placenta previa,   in which the placenta partially or completely covers the cervix. Placenta previa occurs in about 1 in 200 pregnancies, but there is a much higher risk for women aged 35 and older. Placenta previa can increase the risk of premature birth.

After the age of 40, the risk of abnormalities in the child increases

Again, the older an egg cell is, the more likely it is to have chromosomal problems, which can increase the risk of the baby having birth defects. For example, for 25-year-old women, the risk of having a child with Down syndrome, the most common chromosomal condition, is about one in 1,250; by age 40, the risk is about 1 in 100.

Non-invasive blood tests (such as the Fetal DNA Test ) to detect chromosomal problems such as Down syndrome, allow you to obtain information about the baby’s genetic makeup as early as 10 weeks.

There is evidence, albeit limited, that even older fathers may pose some risks to their offspring. A review published in 2019 , for example, found that babies born to fathers aged 45 or older were at higher risk for certain complications such as low birth weight, low Apgar score and premature birth. They also seemed more likely to develop autism, schizophrenia and obsessive-compulsive disorder than the children of younger men. All of these studies are observational, so more research is needed.

So?

There are many pregnancies that go smoothly and without problems at 40 or more. The important thing, in the preconception phase, is to find out well about the chances of success and any risks from your doctor.

Human beings tend to be optimistic. Even when the chances of success on paper may seem little or none. Why, even when everything seems to work against it, can’t you be part of that percentage of women and couples who see their dream of parenthood come true, despite the obstacles?

One of the fortunes of living in this historical moment is that reproductive medicine can help in many ways, with homologous or heterologous assisted fertilization depending on the situation. For some they may seem extreme solutions, for others the only hope of success. Each with its own pros and cons.