Understanding the menstrual cycle is one of the most important steps for anyone trying to conceive. While many people know that ovulation plays a key role in fertility, fewer fully understand how the different stages of the menstrual cycle affect the chances of pregnancy.
Learning how the cycle works can help individuals and couples identify their most fertile days and improve their chances of conceiving.
Understanding the Menstrual Cycle
The menstrual cycle is the monthly hormonal process that prepares the body for pregnancy. A typical cycle lasts around 28 days, although cycles ranging from 21 to 35 days are considered normal for many adults. (NHS)
The cycle is controlled by hormones produced by the brain and the ovaries, which together mature and release an egg and prepare the uterus for potential implantation.
The menstrual cycle is generally divided into four key phases:
- Menstrual Phase
The menstrual phase marks the beginning of the cycle and is when menstrual bleeding occurs. This typically lasts between three and seven days.During this stage, the body sheds the lining of the uterus that developed during the previous cycle. Hormone levels, particularly oestrogen and progesterone, are at their lowest during this time.
- Follicular Phase
The menstrual phase marks the beginning of the cycle and is when menstrual bleeding occurs. This typically lasts between three and seven days.During this stage, the body sheds the lining of the uterus that developed during the previous cycle. Hormone levels, particularly oestrogen and progesterone, are at their lowest during this time.
- Ovulation
Ovulation is the key event in the menstrual cycle when the ovary releases a mature egg. This typically occurs around the middle of the cycle, often around day 14 in a 28-day cycle, although timing can vary.Once released, the egg travels into the fallopian tube, where it may be fertilised by sperm. The egg remains viable for around 12 to 24 hours after ovulation.
- Luteal Phase
Following ovulation, the luteal phase begins. The empty follicle transforms into a structure called the corpus luteum, which produces progesterone.Progesterone helps thicken and maintain the uterine lining, creating the right environment for a fertilised egg to implant. If fertilisation does not occur, hormone levels fall, and the cycle begins again with menstruation.
The Fertile Window: When Are You Most Likely to Conceive?
The most fertile time in the menstrual cycle is known as the fertile window. This includes the five days leading up to ovulation and the day of ovulation itself.
This timing is important because sperm can survive in the female reproductive tract for up to five days, while the egg remains viable for about 24 hours. Having intercourse during this window significantly increases the chances of fertilisation.
For many people with a regular 28-day cycle, the fertile window often falls between days 10 and 15. However, cycle length and ovulation timing vary from person to person, so the fertile window may differ.
Signs That Ovulation Is Approaching
Some people notice physical changes that can help identify when ovulation is approaching. These may include:
- Changes in cervical mucus, which often become clearer, thinner, and more slippery (similar to egg whites)
- A slight increase in basal body temperature after ovulation
- Mild pelvic discomfort, sometimes referred to as ovulation pain
- Increased libido
Ovulation predictor kits can also be used to detect the hormonal surge that occurs shortly before ovulation.
Factors That Can Affect the Timing of Ovulation
While some people have very regular cycles, others may experience variations in ovulation timing due to factors such as:
- Stress
- Illness
- Significant weight changes
- Hormonal conditions
- Age
In some cases, irregular ovulation or the absence of ovulation can make it more difficult to conceive.
When to Seek Fertility Advice
If you have been trying to conceive without success, it may be helpful to seek professional guidance. In general:
- Individuals under 35 are advised to seek support after 12 months of trying to conceive
- Those aged 35 and overmay wish to seek advice after six months
Early assessment can help identify underlying factors affecting fertility and guide the most appropriate next steps.
Supporting Your Fertility Journey
Understanding the menstrual cycle can empower individuals and couples with valuable knowledge about their fertility. By recognising the fertile window and tracking ovulation, many people can improve their chances of conceiving naturally.
Curious about your overall fertility health?
A fertility assessment can be the first step towards understanding your reproductive health and exploring your options. At Manchester Fertility, we offer fertility assessments for couples, same-sex female couples (SSFC), and single women who want to gain a clearer picture of their fertility and plan for the future.
If you have questions about your cycle or fertility, speaking with a fertility specialistcan provide personalised advice and support. Our experienced team is here to help you navigate every stage of your fertility journey with expert care and compassionate guidance.
Call our team on 0161 300 2737
You can also book a free private 1-to-1 consultation with our specialists to discuss starting treatment, orself-refer online.
Last updated: 23rd March 2026
