What age is best to conceive? Do men have a biological clock too?
Age is a big factor when considering fertility. Contrary to public and cultural beliefs, both males and females have a biological clock. As you age the quality of the genetic information in male and female sex cells (or gametes) falls, and as a result of this, there is more chance of infertility, miscarriage and stillbirth in pregnancy and genetic disease and genetic disorders in a child born to elder parents.
A woman’s sex cell (gamete) is known as an egg. It holds half the genetic information, which fuses with a man’s sex cell called a sperm, in sexual reproduction. You get half your genetic information from your mother and a half from your father. The female makes both the gamete sex cell and hosts the fertilisation (her womb is where the egg and sperm join together) and pregnancy. The egg and sperm join to make a bundle of cells known as a zygote. The zygote develops into an embryo and the embryo grows into a child.
The female egg develops in the follicle of the womb, under the signal of follicle-stimulating hormone (FSH), Oestrogen, Testosterone and Progesterone hormone. At day 14 of the menstrual cycle, the egg is released from the follicle as a result of the Luteinizing hormone (LH) and if it meets a sperm in sexual reproduction, it goes on to implant itself in the womb lining and grows into a baby. The male sperm is made in the Testes under the signal of Testosterone hormone and FSH. Oestrogen and Progesterone are also needed to help the Testes develop and for the ejaculation of the sperm in sexual reproduction.
What happens as you age?
As you age the number of eggs a female has falls. At 14–18 there are around 500,000 eggs, 18–31 200,000–300,000 eggs, 31 100000, 21, 75000, 35 50000 and by 40 only 5% or 5000 eggs remain in egg stores. The number of eggs a female has can be tested for by testing her FSH, LH, Oestrogen, Testosterone and Progesterone hormone levels, and her AMH (Anti-mullerian Hormone) levels as well as through an ultrasound of her womb to visually identify the number of eggs in her uterus. As a woman ages her levels of key hormones such as Oestrogen also fall, culminating in menopause around the age of 45–52 years of age. However, some women go through menopause early, with some as young as 30 years of age, and these women therefore are infertile at an earlier age.
As a man ages, their levels of Testosterone fall and Oestrogen increase, and their sperm count falls. After the age of 40, the sperm count and sperm motility (how easily the sperm can swim up the fallopian tubes of the female to meet the egg in reproduction) also falls.
In both a man and a woman, the quality of the genetic information in a gamete decreases as you age. This is because there are more chances for the DNA and RNA which codes for the genetic characteristics of a cell, to become mutated and also there is less DNA repair. Therefore, both the number and genetic quality of sex cells diminish as you age.
What other factors affect conception?
Conception is the production of a fertile offspring in sexual reproduction. Conception is also affected by medical history, with those with endometriosis, chlamydia, diabetes, fibroids, uterine cysts and other female conditions having a high risk of infertility. Chlamydia, erectile dysfunction and low sperm count can also affect a male’s fertility. Weight status can also affect fertility, with those under and overweight producing either too much or too little dietary and body fat. As Oestrogen and Testosterone sex hormones and Cortisol (stress) hormones are made of fat, too low fat and you have too little Oestrogen and too much and you have Oestrogen Dominance and infertility. Stress also increases Cortisol which steals away the fat from the production of Oestrogen and Testosterone, reducing their production and negatively affecting fertility. Dietary Folate (B9 vitamin) and Cobalamin (B12), are also needed to make and repair genetic information needed to make new cells such as sex cells, and so low levels of these key vitamins can negatively affect fertility. It is important to consider all environmental, genetic and lifestyle factors affecting fertility when trying to conceive.
