This is day 4 of your menstrual cycle

Many women feel their hormones rule them at times, so it helps to understand why hormone levels rise and fall.

276 days until your due date

The hormone build-up to ovulation starts now. The pituitary gland at the base of the brain produces follicle-stimulating hormone (FSH), which rises steadily during your period and triggers around 15–20 follicles to develop in each ovary. As well as holding the eggs, these follicles produce estrogen.

Estrogen acts on the pituitary gland, making it release luteinizing hormone (LH), which triggers ovulation. Estrogen is low and steady this week but will rise sharply later in the cycle.

Progesterone is low during your period, starts to rise a few days later, and stays high for the second half of the cycle. It relaxes the cervix muscles, opening the cervical canal, and makes cervical mucus more fluid so sperm can swim through more easily. It also thickens the uterus lining ready for a fertilized egg to implant.

The lowdown

Fertility rites

Folklore fertility tips that call for a leap of faith and a sense of humor:

Use the moon: followers of "lunaception" believe women whose cycles match the lunar cycle (menstruating at new moon, ovulating at full moon) conceive more easily, based on the idea that natural light influences the cycle.
Dance around the Maypole: maypoles are thought to welcome spring and celebrate fertility.

Explainer

Hormones in the menstrual cycle

Four hormones drive the cycle. FSH (follicle-stimulating hormone) rises first, during the period, and starts egg follicles developing in the ovary. Estrogen, produced by the developing egg, climbs and peaks just before ovulation. LH (luteinizing hormone) surges mid-cycle and triggers ovulation. Progesterone rises after ovulation and stays high in the second half of the cycle, thickening the uterus lining.

As a matter of fact

Men get PMS too!

Scientists have described a male equivalent of PMS, called Irritable Male Syndrome. Its mood swings, temper tantrums, and loss of libido were linked to testosterone levels falling because of stress.

This is general information based on NHS guidance, not medical advice, and every pregnancy is different. Talk to your midwife or GP about anything that worries you. If your baby's movements slow down or change, or you have bleeding, severe pain or leaking fluid, call your maternity unit straight away. In an emergency, call 999.