Fertility and Conception
Conception takes place when a woman's egg is fertilised by a man's sperm, resulting in pregnancy. Around 85% of couples conceive naturally within a year of trying to achieve a pregnancy but about one in six or seven couples find they have difficulty conceiving at some time.
How does pregnancy occur?
During a woman's monthly cycle, hormonal changes cause the ovaries to release an egg, which then travels down the fallopian tubes from the ovaries to the womb (uterus). The womb lining becomes thicker with nutrients, ready for after an egg is fertilised in the fallopian tube. If there's no fertilisation that month, the womb lining and some blood is removed - this is what causes a period to happen. The average monthly cycle lasts around 28 days but this often varies from 25 to 35 days, and the first sign of a pregnancy is usually a missed period.
An egg can be fertilised by sperm within 12 to 24 hours of being released. Because sperm itself can survive for up to 5 days inside a woman, fertilisation can happen even if a couple have sex before the egg is released. For most women their peak time of fertility is in the middle of their monthly cycle. However, pregnancy can occur at any time if contraception is not used.
Genes from the father are in the one sperm that fertilises the egg, and genes from the mother are in the egg. Once an egg is fertilised by a sperm, this is known as a zygote. The zygote reaches the uterus around three to seven days after fertilisation. Once implanted to the nutrient-rich wall of the uterus, the zygote starts growing.
If you think you may be pregnant, a pregnancy test of your urine done several days after a missed period can confirm it. Test kits can be bought from pharmacies or can be obtained through your doctor, sexual health clinics, and family planning clinics.
What can affect fertility?
For most couples, having a baby is straightforward - by having regular and unprotected sex. Infertility – difficulty in becoming pregnant - can be due to problems in the man, the woman, a combination of both partners or in some cases, no identified reason. A couple will be diagnosed as having an infertility problem if they have not had a baby after trying for two years.
Infertility may be classified as primary infertility, where someone who has not conceived a child before has difficulty conceiving, and secondary infertility, where a person has had a pregnancy or pregnancies in the past, but is now having difficulty conceiving.
Common conditions affecting a woman’s fertility include:
- Damaged fallopian tubes
- Ovulation problems
- Endometriosis (where small pieces of the womb lining are found outside the womb)
- Uterus conditions
- Age - female fertility declines considerably after 35
- Polycystic Ovary Syndrome (PCOS)
- Previous ectopic pregnancy (where the zygote implants outside of the womb) or more than one miscarriage
- Diabetes, epilepsy, thyroid and bowel diseases
- Stress, being overweight or underweight and smoking
In men, infertility may be due to:
- A low sperm count or low sperm quality
- Problems with tubes carrying the sperm
- Erection problems
- Ejaculation problems
- Inflamed testes (orchitis)
- Previous bacterial infection affecting tubes within the epididymis
- Medical treatment such as radiotherapy or surgery to correct conditions such as hernia, undescended testes or twisted testicles
- Genetic problems
- Being overweight
- Contact with chemicals or radiation at work
- Age (the extent at which male fertility starts to decline with age is unclear)
- Cannabis and other drugs, including alcohol abuse.
What help can I get with infertility?
If conception has not happened after a year of unprotected sex, see your doctor for advice. Couples with infertility risk factors, such as the woman being over 35, may want to seek advice sooner.
What tests might be required?
Infertility tests for women include blood tests, checking for levels of progesterone - to check for ovulation - hormone blood tests for irregular periods to check for levels of follicle-stimulating hormone (FSH) and luteinising hormone (LH), and a thyroid function test. A swab test is also usually done for Chlamydia, a common sexually transmitted infection which can affect fertility. More specialised tests include a hysterosalpingogram X-ray where a special dye is put into the womb and fallopian tubes to check for blockage of the fallopian tubes, and a laparoscopy (“keyhole” surgery) where a special camera is passed through a small incision in the abdomen to look closely at the womb, fallopian tubes and ovaries.
For men, infertility tests include a physical examination to check the testicles and penis for any lumps or problems, a semen analysis for sperm count, sperm mobility or abnormalities, and a Cchlamydia test.
The treatment of infertility depends on the results of tests and the medical history, and treatment for underlying conditions affecting fertility may be recommended.