Healthy men in their 70s and beyond can still father children, however the time taken for a partner to become pregnant is longer when a man is middle-aged or older. Reasons for this may include a decrease in sexual activity, lower semen volume, changes to sperm motility (movement), a lower number of motile sperm, and possibly lower sperm function and DNA quality.
Female and male fertility decrease with age. For women fertility starts to slowly decline when they are in their early thirties. Around age 35 the decline speeds up and by age 40 the chance of conceiving has fallen by half.
The biological reason for this is that, as women age, the total number of eggs in their ovaries and their quality decline. The average age of menopause is about 51 years (and this has not changed over the centuries) and this marks the absolute end of fertility but in fact, it is rare for a woman to conceive in the 10 years leading up to menopause. In part this is because the quality of the eggs that are released is compromised; at age 40 about 75% of eggs are chromosomally abnormal which reduces the chance of pregnancy and increases the risk of miscarriage.
For both men and women, having a healthy body weight and being physically active will help fertility and give the best chance for a healthy child. There is ongoing research into why being obese can affect sperm production and quality in men.
Most people understand that smoking increases the risk for heart, vascular, and lung disease. Many do not realize that smoking can also lead to problems with fertility in both men and women. Erectile dysfunction and pregnancy complication rates are also increased with smoking.
Male smokers can suffer decreased sperm quality with lower counts (numbers of sperm) and motility (sperm’s ability to move) and increased numbers of abnormally-shaped sperm. Smoking might also decrease the sperm’s ability to fertilize eggs.
Men whose mothers smoked half a pack of cigarettes (or more) a day had lower sperm counts. Smoking during pregnancy also can lead to growth restriction of the baby before birth. Children born with lower-than-expected birth weights are at higher risk for medical problems later in life (such as diabetes, obesity, and cardiovascular disease). Children whose parents smoke are at increased risk for sudden infant death syndrome (SIDS) and for developing asthma. (X)
(American society for reproductive medicine)
Alcohol can reduce both male and female fertility but it is not clear what levels are a risk. While it is not established exactly how alcohol impairs female fertility, research shows that even drinking lightly can reduce the likelihood of conception. In men alcohol, can impair fertility because it can cause impotence, reduce libido and affect sperm quality.
Diet and vitamins
Foods including pumpkin seeds, parsley and vitamins such as zinc, vitamin E and B12 are promoted as improving fertility in men. While there is no strong scientific evidence to show that specific foods or natural therapies improve fertility, having a healthy diet is important for general health and wellbeing, especially when trying to start a family.
When you want to have a baby you can improve the odds of this happening if you have sex during the ‘fertile window’ of the menstrual cycle.
Ovulation is when an egg is released from the ovary. This happens two weeks before a period starts. Technically, pregnancy is possible during the six days leading up to and including ovulation. But, the likelihood of pregnancy is dramatically increased if you have intercourse during the three days leading up to and including the day of ovulation.
The length of a woman’s menstrual cycle determines when ovulation occurs:
If all this seems too complicated, an alternative is to have sex every two to three days – that way you are sure to cover all bases without getting too technical about when the chance of conceiving is greatest.