When is the right time to have a baby?
Delayed child bearing is becoming increasingly common in western societies for example, in the United Kingdom the mean age of childbearing has risen over the last 40 years from 23 in 1968 to 29.3 in 2008. There are several reasons: many couples prefer to rear their children only after establishing a stable relationship and financial security, also, there are increasing numbers of late and second marriages.Furthermore, there may be a delay in finding the right partner till later? Or a partner may have a medical problem that need to be sorted first.
The relationship between age and fertility
Although pregnancies in women approaching 50 and beyond are occasionally reported, there is a decrease in fertility (the ability to achieve a pregnancy) with advancing age. The decline is gradual over the reproductive life span of the woman; it is particularly noticeable over the age of 30 and accelerates between 35 and 40 so that fertility is almost zero by the age 45. Most women will be able to conceive naturally and deliver a healthy child at term , but the proportion who experience infertility, miscarriage or fetal abnormality increases rapidly thereafter. At the age of 25 just 5% of women takes longer than a year to conceive with regular intercourse, rising to 30% in those aged 35. Only two in five of those who wish to have a child at 40 years of age will be able to do so.
The risk of miscarriage is also increased with ageing e.g. the risk of miscarriage at age 25-29 years is 10% while the risk at age 40-44 is 34%. Furthermore, advanced maternal age is associated with an increased risk of chromsomally abnormal offspring. Older women are also at increased risk of obstetric complications such as gestational diabetes, pre-eclampsia, placenta praevia, caesarean section, fetal growth restriction, premature birth and the risk of stillbirth.
Why does fertility decline with increasing age?
- Ageing of the ovaries is the most prominent factor and is part of the normal ageing changes that affect all organs and tissues. Most women have about 300,000 eggs in their ovaries at puberty. For each egg that matures and is released (ovulated) during the menstrual cycle, at least 500 eggs do not mature and are absorbed by the body. By the time the woman reaches menopause which usually occurs between 50-55 years, there are only several thousands eggs remaining. As the woman ages, the remaining eggs in her ovaries also age, the old egg cells become riddled with DNA damage because their DNA repair systems wear out making them less capable of fertilization and their embryos less capable of implanting. Although lifestyle features such as smoking can alter the rate of depletion of the follicles, it is largely genetically determined.
- Fertilization is associated with a higher risk of genetic abnormalities e.g. chromosomal abnormalities such as Down syndrome with increasing age. The risk of a chromosomal abnormality in a woman age 20 years is 1/500 while the risk in woman age 45 is 1/20.
- Gynecological problems such as pelvic infection, tubal damage, endometriosis, fibroids, ovulation problems etc tends also to increase with age. Also the possibility of premature menopause. As the woman gets older, she has more time to develop these conditions, which will adversely affect her fertility.
- Sexual function is also decreased with ageing e.g. libido, frequency of intercourse etc.
- The effect of ageing in endometrial receptivity (ability of the endometrium to receive the embryo) is controversial. There is increasing evidence that the receptivity decreases with age.
- Ageing does not just affect women, but also men to a much lesser degree. It affects sperm quality and coital frequency. There is no maximum age at which men are not capable of conceiving a child. One study reported that for men below the age of 25 the average length of time it took for their partners to get pregnant was 4.6 months compared with nearly two years for men over the age of 40. A recent study from Brazil showed that the chance of fathering a child fell by 7% for every year above the age of 41 (ASRM 2011)
- Advanced maternal age increases the risk of autosomal dominant diseases such as Marfans syndrome, neurofibromatosis and achondroplasia.
Investigations of infertility in older women
- It is advisable to seek the advice of your doctor/ specialist sooner than later so investigations and treatment can be started without undue delay.
- Several tests may be useful in assessing the fertility potential in older woman e.g. blood tests to examine the levels of the hormones FSH, LH, estradiol and inhibin on day 3 of your menstruation.
- You will be more likely to be counseled about the risk of miscarriage and chromosomal abnormalities in relation to your age. In addition to the potential complications of pregnancy such as high blood pressure, bleeding and diabetes.
Treatment options for infertility in older women
There are limited options for treating older women who are menopausal or perimenopausal. Older women usually respond poorly to ovarian stimulation and the live birth rates even with IVF treatment are significantly lower than with younger women.
|Age||40||41||42||43||44 and over|
|Live birth rate per egg collection||15%||11%||8%||5%||2%|
Data adapted from SART report 2000
In addition, older are at increased risk of having medical problems in their pregnancies and deliveries such as gestational diabetes, placenta praevia, abruption, caesarean section, premature birth, blood clot etc. In order to improve the success rate of IVF treatment in older women, some clinics recommend assisted hatching, blastocyst embryo transfer, preimplantation diagnosis and only transfer normal embryos. Furthermore in some countries the transfer of high number of embryos is recommended. Other options of treatment include:
- Egg donation using eggs donated by younger woman. Bewley and Ledger (2009) reported that more than half the IVF live births in women over the age of 40 have used donor eggs.
- Embryo donation if the male partner also has a sperm problem.
- Surrogacy if a woman (traditional surrogate) agrees to become pregnant using the male partner sperm and her own eggs.
- Adoption and foster care.
- Accepting child-free living.