How Men and Women Calculate Most Fertile Days

While conceiving a baby is a natural occurrence, increasing numbers of people around the world are finding that it is not as easy as it might seem. Male fertility rates have been steadily falling over the past fifty years, leading the World Health Organisation to downgrade the levels used to measure healthy sperm in 1999. It is therefore important to understand for Men and Women alike how to calculate most fertile days.


Fulfill your wish for children by learning about

Why it is so important to time your Baby-Making Sex
How men and women can calculate their most fertile days
What men can do to improve the quality of their sperm


Even in males whose sperm levels are classified as normal, up to 85 per cent of ejaculate can contain abnormal forms, which can lead to miscarriage, birth defects and aneuploidy1.

Click the button to read our comparison of the top 12 male fertility supplements

the quality of sperm has been falling dramaticallyVarious explanations have been put forward for this reduction in sperm quality, from rising levels of oestrogen in drinking water to poor nutrition.

It means that couples need to find ways to increase their chances of conceiving and having a healthy pregnancy by making sure that a healthy sperm meets a healthy egg at the optimum time.


BSM Timings for Women

There are about six days in every month when a woman is at her most fertile. These fertile days begin around five days before ovulation, and finish on the day of ovulation.

women have to be aware of their ovulation dateAfter being released from the ovaries, an egg begins to die and fertility decreases, so BMS will not be effective in the days after ovulation. During these fertile days the mucus in the cervix is thinner and clearer than usual, allowing sperm to travel more easily into the uterus.

While it is possible to get pregnant on other days of the month, this ‘fertile window’ that occurs around the time of ovulation is when pregnancy is most likely, with the day before ovulation being the very best day to practice BMS. Even in women who have a regular menstrual cycle, studies have shown that predicting the day of ovulation solely by measuring the cycle is very inaccurate2.

There are several more reliable ways to discover when the day of ovulation will occur, including measuring the female temperature over the course of the month, examining the cervical mucus and the cervix and measuring levels of hormones in the urine. Measurements can be taken using cycle computers or ovulation tests. Having BMS in the fertile window will be ineffective, however, without good amounts of healthy sperm to fertilise the egg.

Click the button to read our article on the top six ovulation tracking tools

BSM Timings for Men

While it is often assumed that the more often that sperm enter the female body during the fertile days the more chance there is of conceiving, this has been found not to be the case. Optimal specimens of semen occur when there is an ejaculation every two or three days.

too many ejaculations can reduce the number of fertile sperm in the semenRepeated ejaculations in a time period of 24 hours or less will cause the numbers of sperm to reduce by as much as 30 per cent. This also results in diminished muscular contractions, meaning sperm have further to travel unassisted. The popular approach of ‘repeat performances’ during a fertile period is not actually increasing the chance of conception, as after the first ejaculation there will be a very limited number of sperm.

On the other hand, leaving too long an interval between ejaculations has a negative effect on sperm production too. After two or three days without an ejaculation, the number of sperm with good motility in a sample of semen will decrease progressively. Sperm motility is the ability to swim in a forward motion towards the egg.

Increasing Sperm Production and Quality

Due to the high variance in male sperm quality men attempting to father a child are advised to make some simple behavioural changes, adjust their diet and if possible take a male fertility supplement.  Studies have shown that sperm counts can be increased by up to 215 per cent, sperm motility can be increased by up to 23 per cent and ejaculate volume by up to 33 per cent when the male diet is supplemented with specific micronutrients3.

Male sexual hormones are closely linked to fertility. Raising the levels of this hormone by supplementing with Vitamin D and zinc has been found to extremely effective. A study of male rats in 1989 found that the fertility of their sperm was reduced by 73 per cent when their intake of Vitamin D were restricted, and their sperm production and mating success was reduced by 45 per cent4.

Zinc plays a vital role in the development of genetic materials like DNA and proteins, and men with zinc deficiency often display low levels of male sexual hormones, which will cause sperm to be less healthy and less mobile. Another element that plays a vital role in sperm production is selenium, and many studies have linked low levels to male infertility5.

Click the button to read our comparison of top 12 male fertility supplements


To summarise, the very best baby making sex will take place every two or three days during the monthly window of six or so fertile days, with the day before ovulation the optimum day. Taking supplements that contain Vitamin D, selenium and zinc for at least three to six months beforehand will ensure that male fertility is at its peak and sufficient amounts of good quality sperm with high motility will be produced.

The market has on offer a wide range of male fertility supplements. All products differ significantly in terms of nutrients on offer and price. Menfertility.org has carefully compared 10 of them in terms of value for money and nutrients provided.

Click the button to read our comparison of top 12 male fertility supplements


Studies cited:

  1. “Aitken RJ, Sawyer D, Discipline of Biological Sciences, Centre for Life Sciences, University of Newcastle, Australia http://www.ncbi.nlm.nih.gov/pubmed/12817679
  2. “http://www.bmj.com/content/321/7271/1259”
  3. “Micronutrient Supplementation Increases Sperm Quality in the Sub-fertile Male’ by Martin Imhof, Jakob Lackner, Markus Lipovac, Peter Chedraui, Claus Riedl European Urological Review, 2011;6(2):120-3) http://www.urology-hub.com/articles/micronutrient-supplementation-increases-sperm-quality-sub-fertile-male”
  4. “http://www.ncbi.nlm.nih.gov/pubmed/2723823?dopt=Abstract”
  5. “Oguntibeju OO, Esterhuyse JS, Truter EJ. Selenium: its potential role in male infertility. Pak J Med Sci 2009;25(2): 332-337 http://pjms.com.pk/issues/aprjun109/article/reviewarticle1.html”
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