It's possible to fall pregnant with your first and struggle with your second.

Secondary infertility is a surprisingly common problem – but for affected couples, it can be devastating.

In a nutshell, it occurs when couples struggle to fall pregnant the second time around after a year or more of trying, when the first time was relatively easy.

The Motherish recently spoke with City Fertility Centre Sydney medical director Dr Georgiana Tang to find out about this common condition – and how to beat it.

She said that while official statistics weren't known, experts believe it affects around one in 10 Australian couples. However, she said there was a also a lack of awareness about the condition.

"Overall, there is a lack of awareness about secondary infertility but these days with the internet it’s easier. But then sometimes there’s too much information, and people looking on the internet can get confused and worried," she said.

“Sometimes it’s hard for people to accept. There’s the expectation they’ll fall pregnant because they have already. People who have never fallen pregnant are anxious and on the other hand, people who have been pregnant have that expectation. It’s a different type of pressure," she continued.

WATCH Dr Alan Copperman discuss secondary infertility below...

Dr Tang advised couples to seek medical advice sooner rather than later.

"If we find out early, we can intervene early. Don’t feel bad about yourself – it’s all right to seek help. There’s things we can do to help," she added.

Dr Tang said there were several main causes of secondary infertility:

1. Maternal age.

Normal, healthy couples have a 20-25 per cent chance of conceiving each menstrual cycle.

But once a woman reaches 35, fertility starts to decline - and once she hits 40, her conception rate is in the range of 8-10 per cent per month. By age 43, the pregnancy rate could be as low as 1-3 per cent per month.

2. Female factors.

Irregular menstrual cycles could indicate a problem with ovulation, which could then affect fertility.

Blocked fallopian tubes are also a common cause of secondary infertility, occurring when the egg can’t meet the sperm normally due to a blockage.

3. Male factors.

Poor sperm function is another common cause of secondary infertility.

According to Dr Tang, developing and transporting mature, healthy, functional sperm depends on a specific sequence of events occurring in the male reproductive tract - and many disturbances can occur along that path.

4. Lifestyle.

Being over or underweight can affect your chances of falling pregnant - for both men and women. Diet, exercise, smoking and alcohol consumption should also be examined.

5. Unknown causes.

However, around 10 per cent of infertility remains unexplained even after a complete medical evaluation.

Have you ever struggled with secondary infertility?