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How Likely Actually are You to Get Pregnant Each Month?

Getting pregnant is more complicated than you might think.

Getting pregnant is, on paper, very straight-forward. You have sex without contraception, the sperm does its thing with the egg, and hey presto! You're expecting a baby.

 

But considering there are over 12,000 searches for 'how to get pregnant' each month in the UK alone, it seems it's far more complicated than we were led to believe in sex education classes at school.

 

Did you know, for example, that women under the age of 30 (who aren't using contraception) are thought to have only a 20% chance of getting pregnant each month? By the age of 40, this drops to about a 5% chance. These statistics were calculated after analysing studies that looked into the chances each cycle of a woman becoming pregnant, and the findings were published in the American Society of Reproductive Medicine.

 

How long does it take to get pregnant?

Based on this information, a woman under 30 who has no fertility issues is likely to get pregnant within the first six months. But if this doesn't happen for you, you shouldn't worry.

 

The UK NICE (National Institute for Health and Care Excellence) clinical guidelines state: "In the general population, more than 8 out of 10 couples where the woman is aged under 40 will get pregnant within 1 year if they have regular sexual intercourse (that is, every 2 to 3 days) and do not use contraception. More than 9 out of 10 couples will get pregnant within 2 years."

 

How do you get pregnant?

As mentioned, it's more complicated than just... having sex and keeping your fingers crossed. Get ready for a science lesson! 

 

Pregnancy is only possible from about five days before ovulation, through to the day of ovulation. That's what's called the 'fertile window', so having plenty of sex during these days will boost your chance of getting pregnant.

 

"Pregnancy depends on many factors happening inside a woman’s body occurring correctly and at the right time," Clinical Research Director Dr Sarah Johnson tells Cosmopolitan. "Firstly, she has to ovulate, which depends on her hormones being at the right levels. For the best chance of getting pregnant, the sperm should be already present in the reproductive tract before ovulation – so it is there ready to fertilise the egg as it travels down the fallopian tube." The egg is only viable for about 24 hours once it is ovulated, so the quicker the better, basically.

 

But because women's cycles are so unique (and vary greatly in length), getting the timing exactly right for pre-ovulation sex can be tricky. "The timing is right when the oestrogen levels rise," explains Dr Sarah. "This changes the female reproductive tract from being a sperm-hostile environment (where it can survive for only minutes), to a sperm friendly environment, where they can live for five days or more and so journey to the fallopian tube ready for fertilisation."

 

The expert notes that "women cannot know the day they ovulate just by looking at their dates" - despite many period tracking apps 'calculating' ovulation dates by this means alone. Three ways to find out the optimum time to have sex if you're trying to get pregnant include:

 

Tests that measure oestrogen

Measuring your basal body temperature (your temperature when you first wake up, which rises when you ovulate)

Checking cervical mucus, which changes consistency

If all goes well, the sperm meets the egg - and both are healthy - they will create an embryo. At which point, "the woman’s uterus needs to be in a receptive state at exactly the right time to allow the embryo to implant and develop into a baby," explains Dr Sarah.

 

But this doesn't always happen, and the reason why is an area that's still being explored by medical experts. "There is a lot of research happening at the moment to try and understand why this does not always happen, but there is a lot we still don’t know. This is why for a lot of women and couples who fail to become pregnant, their final diagnosis is 'unexplained infertility' – i.e. we don’t know why it hasn’t happened," notes the doctor.

 

What lifestyle factors can affect my chance of getting pregnant?

Some lifestyle factors are known to increase or decrease that 20% likelihood of conceiving each month.

 

"Smoking has been shown to reduce fertility, and this includes second-hand smoke if you live with a partner who smokes," Professor Joyce Harper, a Professor of Reproductive Science at the Institute for Women’s Health, UCL, tells Cosmopolitan. "Being underweight or overweight can both increase the time it takes to get pregnant. Sometimes menstrual cycles stop altogether for women who are very underweight, and of course you cannot get pregnant naturally unless you are ovulating, so these women should speak to their doctors straight away to get help," she advises.

 

"Polycystic ovary syndrome (PCOS) can be associated with being overweight, and this also causes problems with ovulation. Help is available once PCOS is recognised, so if you have very erratic cycles speak to your doctor," suggests the professor.

 

Other affecting factors include:

 

+ Having a healthy diet

+ Regular exercise is recommended

- Some jobs can affect fertility, for example if you are using pesticides or exposed to X-rays

- There are a whole host of medicines that affect fertility, speak to your doctor to find out if there are any fertility-friendly alternatives

- Excessive drinking (above the recommended weekly allowance) can affect a man's semen quality

- Temperature plays a part for the man, so loose fitting underwear like boxer shorts that won't heat up the scrotal area is advised

- Sexually transmitted infections (including HIV and genital tuberculosis) can reduce fertility

- Other health conditions including mumps after puberty, an undescended testicle, polycystic ovary syndrome, endometriosis and menstrual cycle problems can negatively affect fertility

What are the chances of getting pregnant at 40?

Women are born with all the eggs they are going to have, which is why female fertility declines with age - particularly so from the age of 35. By age 37, 90% of a woman's eggs are gone, which is why the likelihood of getting pregnant at around age 40 is just 5% each month.

 

"The quantity and quality of eggs declines with age," Dr Sarah Johnson tells Cosmopolitan. "It is not a sharp drop by age 40, but a continuous drop from birth. Women are born with 1-2 million eggs, and from puberty we lose about 1,000 a month until the menopause. The quality of the eggs goes down as the chromosomes in the egg are fragile and the older they are, the more likely the chromosomes can become muddled.

 

"This leads to an increase in infertility and miscarriages, and the chance of having a child with a chromosome abnormality," explains the doctor.

 

Starting from puberty, men produce sperm all their life, but the quality declines with age. When the male partner is over the age of 45, there is an increased risk of miscarriage and certain conditions in the offspring, such as autism.

 

How long should I try to get pregnant for, before seeing a doctor?

"Speak to your doctor if you are under 35 and have been trying for one year without success," says Dr Sarah. "If you are 35-40, go after 6 months, and if you are 40 speak to your doctor straight away."

 

When should I start trying for a baby?

Really, it's each to their own. Firstly, not everyone knows if they want children, so try not to feel pressured into doing anything you're unsure about just because it seems to be the 'done thing'. For Professor Joyce Harper, she simply wants women to know the facts about their fertility. That way, they can make that decision if and when it's right for them.

 

"I aimed to have kids at 30 but was with a partner who was not ready," Joyce tells Cosmopolitan. "I met someone who was ready at 35 and we tried immediately. Nothing worked, so we started on our fertility journey which was long and difficult. I delivered my first child just before my 40th. I do not want women to go through what I did," she admits. "For many years I thought I would be childless, but I didn't want to be."

 

Generally, women are leaving it later and later to have children, with the average age that women have their first child in many countries now being over 30 years. "In the UK, 20% of women are childless, and we do not know how many of these are by choice or by circumstance. We want to be sure that men and women understand their fertility so they can make fully informed choices about their reproduction," explains the professor.

 

Some more fertility facts:

 

Most people get pregnant within a year of trying

In one ejaculate, men produce about 100 million sperm

Once a month, a woman produces one egg – meaning she only ovulates about 500 eggs in her whole lifetime

Women and men should aim to be as healthy as possible before they start trying for a baby, including limiting alcohol and caffeine

The chance of having a baby after one IVF attempt is around 30% for women aged under 35, 10% for women aged between 40 and 44, and over 45 it's almost zero