Pregnancy's Biological Clock
Women in their 30s and 40s naturally fall in the likelihood of becoming pregnant. The biological clock works.
The biological clock is a scientific term that refers to the circadian rhythms which govern sleeping and waking cycles in living organisms.
The biological clock refers to fertility . Human biology, despite social expectations, dictates that chances for pregnancy decline with age. The number and viability of eggs decreases as a woman approaches 40.
"This is a natural process," says Zain Al-Safi, MD, an obstetrician-gynecologist who specializes in reproductive endocrinology and infertility.
"We have a longer life expectancy than our ancestors. Dr. Al-Safi states that the ovaries should be capable of reproducing by 44 years old. So now, women are living longer than ever before. It's almost like they live twice as long. The biology hasn't caught up. After age 32, women see a decrease in their chances of having children. Then, it gets more dramatic after 35-37.
How do you cause your pregnancy rate to decrease with age? Dr. Al-Safi explains that two factors are responsible for the decline in pregnancy rates as women age.
A decrease in eggs available, or oocytes, is the first. All the eggs that female babies will ever receive are usually one to two million. However, by puberty, the average number has dropped to around 300,000. A gradual decline in available eggs continues until menopause.
Dr. Al-Safi states that the majority of these eggs don't go through ovulation. They are instead lost during atresia. Atresia is a natural process in which oocytes degenerate naturally before reaching the ovulation phase. He says that atresia can increase as a woman gets older.
However, Dr. Al-Safi states that it's not just the availability of eggs that has most impact on pregnancy rates. Quality is more important than quantity. Cellular division doesn't work as well with older eggs as it does with eggs of a younger age.
He explained that an egg cell needs to divide before the process of ovulation. The egg is a single cell with 46 chromosomes. The egg should be able to divide in order to produce 23. A sperm that also contains 23 chromosomes might fertilize it to create an embryo with 46. Dr. Al-Safi states that age may affect division.
He says that the separation might not occur properly and an egg could end up with more or less chromosomes. The egg will not be 46 when it is fertilized with a 23-chromosome, sperm.
The majority of these embryos are not likely to implant within the uterus. Therefore, pregnancy rates will decline with increasing age. However, some of these embryos may not implant and cause miscarriage . This is significant as it also increases with the age. Both of these could lead to a decrease in live births with increasing reproductive age.
Dr. Al-Safi states that age may also have an indirect effect on fertility. This is because conditions like uterine fibroids and endometriosis as well as treatment such as chemotherapy can affect the ovaries.
What does paternal gender have to do with pregnancy? When it comes to having a healthy baby and creating that child, paternal age is important. Dr. Al-Safi explains that age affects both sperm quantity and quality.
His statement: "We see significant changes in the analysis of semen with age." The concentration motility, which is the movement of the eggs, and the normal form, or morphology would both be affected by age. What about the effects on pregnancy chances? But it's not as prominent."
Dr. Al-Safi argues that an older paternal age (typically 50 years old) can raise the chance of certain genetic conditions like dwarfism. There may also be an increase in miscarriage risk due to changes in sperm health . He also says that older men may have a higher risk of schizophrenia in their offspring. A higher risk of autism can also be associated with older paternal ages.
What is the ideal age for starting a family? Peak fertility for women generally occurs before the age of 32. However, Dr. Al-Safi recognizes that not everybody is ready to start their own family.
If you are in your 20s and 30s, consider freezing embryos or eggs. Dr. Al-Safi states that frozen embryos or eggs can be used later and lead to a successful pregnancy.
He says that women who decide not to freeze embryos or eggs and want to get pregnant after their 40s have many options. Natural pregnancy may not be possible. However, fertility treatments like in vitro fertilization can help increase your chances. If you have a chromosomally-normal embryo, or if they are unavailable, eggs from an older donor might work. This significantly improves the likelihood of pregnancy.
His explanation is that "if she did have chromosomally-normal embryos, then her chances of getting pregnant would be comparable to someone aged 30 who received a transplant of an embryo chromosomally abnormal." The pregnancy rates would be similar if the embryo was transferred to a recipient aged 44 or 30, as long as there is no abnormality in the uterus.
Dr. Al-Safi points out, however that IVF is not offered at UCLA to older women. This is because there are too few chances of pregnancy to warrant the IVF treatment and the egg harvesting.
Other complications that may arise in pregnancy for women older than 35 include high blood pressure, diabetes, and gestational hypertension.
The biological clock can be an unnatural phenomenon. However, fertility preservation methods can slow the time down a bit. The best time to get pregnant is before the clock goes down.
Dr. Al-Safi advises couples that they should try to have children as soon as they are ready.