Trying for a baby? You should have sex ALL month long

Having sex even outside a woman’s ‘fertile window’ can boost the chances of having a baby, according to research.

Scientists found that regular sex throughout the month alters the woman’s immune system, making her body more hospitable for pregnancy.

The changes to her immune system mean her body is less likely to reject sperm or an emerging embryo as a ‘foreign invader’, they said.

So at ovulation - when an egg is released from the ovaries, around the middle of the menstrual cycle - her body is better prepared to conceive.

‘It’s a common recommendation that partners trying to have a baby should engage in regular intercourse to increase the woman’s chances of getting pregnant – even during so-called ‘non-fertile’ periods – although it’s unclear how this works,’ said lead author of the study, Dr Tierney Lorenz.

‘This research is the first to show that sexual activity may cause the body to promote types of immunity that support conception.

‘It’s a new answer to an old riddle: How does sex that doesn’t happen during the fertile window still improve fertility?’

The ‘fertile window’ begins five days prior to ovulation and ends the day after the egg is released.

For the study, researchers from Indiana University used data from the menstrual cycles of 30 healthy women.

Half the women were sexually active and half did not have sex at all.

The researchers found that women who were having intercourse experienced more beneficial changes to their immune systems that would allow a pregnancy to occur.

Specifically, the sexually active women had greater changes in their helper T cells.

There are several types of these cells: Type 1 helper T cells assist the body with defence against outside threats, while type 2 helper T cells help the body accept those aspects of pregnancy the body may otherwise interpret as ‘foreign invaders’, such as the presence of sperm or emerging embryo.

The sexually active women had significantly higher levels of type 2 helper T cells during the luteal phase of the menstrual cycle, when the lining of the womb thickens in preparation for pregnancy.

They had higher levels of type 1 helper T cells during the follicular phase in the menstrual cycle, when the ovary is preparing to release an egg.

The sexually active women also experienced beneficial changes to the levels of antibodies secreted by their white blood cells, which the sexually abstinent women did not.

‘The female body needs to navigate a tricky dilemma,’ said Dr Lorenz.

‘In order to protect itself, the body needs to defend against foreign invaders.

‘But if it applies that logic to sperm or a foetus, then pregnancy can’t occur.

‘The shifts in immunity that women experience may be a response to this problem.’

He added: ‘We’re actually seeing the immune system responding to a social behaviour: sexual activity.

‘The sexually active women’s immune systems were preparing in advance to the mere possibility of pregnancy.’ 

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