Infertility - Introduction

Pre-pregnancy advice

Normal Conception

Infertility Investigations

Causes And Management Of Infertility

Semen needs to be ejaculated close to the cervix. Sperms penetrate the cervical mucus, leaving the seminal fluid behind in the vagina (so don't be concerned that it runs away afterwards). The sperms are stored in the mucus in the cervical canal for a day or two, and released in a steady stream to swim up through the womb into the fallopian tubes to meet the egg, which is released each month either from the left or right ovary.

Sexual intercourse is best timed when the cervical mucus is at its best and most receptive to sperm, a day or two before ovulation. In that way a constant supply of sperm is provided ready for the egg as soon as it is released.

When the egg follicle in the ovary is fully grown it ruptures to release the egg, which was loosely attached to cells lining the follicle. The egg is picked up by the finger-like fimbria of the tube and is wafted along the tube, between the folds of its lining which has microscopic fronds (cilia) that beat towards the womb (uterus).

Fertilisation of egg and sperm occurs in the tube, and the newly fertilised egg (now called an embryo) begins to divide and subdivide, into 2, 4, 8 cells etc. It remains in the tube for several days before reaching the uterus. There it begins to implant itself in the lining of the uterus (endometrium) about 7 days after ovulation, and after implantation the embryo is able to grow in size for the first time.

Soon after implantation the hormone HCG from the embryo can enter the woman's blood, and so stimulates the ovarian follicle (now called a corpus luteum) to keep functioning and continue to produce the hormone progesterone. That in turn continues to support the endometrium and prevents menstruation occurring, which is the first sign of pregnancy. HCG can be detected in the woman's blood and urine, and is the basis of the usual pregnancy tests. Later the pregnancy can be seen by ultrasound (echo) scanning.

See also:

• Infertility - Introduction
• Pre-pregnancy advice
• Fertility Investigations
• Causes And Management Of Infertility

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