There are several reasons potentially underlying fertility issues.

Approximately 3.5 million people will struggle to conceive naturally.

It's not an insignificant figure, amounting to one in seven couples, meaning someone you know may very well be having a hard time trying to have a baby.

It may even be a situation you're all-too familiar with personally. Women are very much aware of which factors can cause fertility issues.

We're all told, among other things, to not leave it too late. But it remains that many of these factors are outside of our control.

Shedding some light on this matter is Dr Anne Poliness of City Fertility Centre in Melbourne, who speaks about the six key reasons women aren’t able to immediately fall pregnant.

1. Blocked fallopian tubes

Sperm may be prevented from meeting the egg if the fallopian tubes are blocked.

According to Dr. Poliness, the reasons behind blocked fallopian tubes may be either endometriosis or previous pelvic infections.

One possible solution is surgery removing external scarring to unblock the tubes. IVF treatment can also bypass damaged or blocked tubes.

2. Irregular cycles

Although irregular menstrual cycles may lead to problems with ovulation, and are not always dangerous, it's important to look into what's causing the irregularity.

To treat irregular cycles - especially for those who are trying to conceive, Dr. Poliness suggests the use of medication such as Clomid or a follicle stimulating hormone.

3. Fibroids

Non-cancerous masses located in the uterus or cervix, how much fibroids effect fertility depends upon their size and location. Most fibroids do not need surgery.

Dr. Poliness stresses not all gynaecologists would say, for certain, whether fibroids cause infertility. However, she also points out it's useful to have an understanding of the damage they cause.

While surgery is not always necessary, there is a small risk the uterus may have to be removed, in which case surgery should be given some serious thought.

4. Endometriosis

Dr. Poliness says although another cause of infertility could be endometriosis, there's not necessarily any correlation between how severe your condition is and your chances of conceiving.

Endomtriosis can also be extremely painful. "It doesn't have to be severe endo to change the body parts that make it hard to conceive," she explains.

To experience difficulties conceiving naturally, endometriosis can be on the ovaries, tubes or even behind the uterus.

A laparoscopy to remove endometriosis can improve the chances of natural conception.

5. Polycystic Ovary Syndrome

With PCOS, the ovaries secrete large amounts of testosterone which interferes with ovulation, which in turn leads to fertility issues.Women with PCOS need not go on hormone suppressants, such as the pill

Not only have this, but women who have PCOS enlarged ovaries that contain multiple small cysts.

"For women with PCOS the main issue is how frequent the periods are. If someone has a cycle every four or five weeks, it's not always necessary to be on hormone suppressants.

However, if the cycles are every three or six weeks it might be necessary," Dr. Poliness says.

In terms of treatment, ovulation may also be induced with a medication called clomiphene.

There is a high success rate with this drug, resulting in pregnancy rates comparable to that of the general population.

Otherwise, in vitro fertilisation (IVF) is another option for women who cannot conceive after other options haven't worked.

6. Age

The one we're all hyper-aware of.

Dr. Poliness believes the best conception rates for normal healthy couples are 20 to 25 per cent per menstrual cycle.

Your chances do decrease with age

However, by the time we're 40, a woman's natural conception rate is at just five to eight per cent per month for the first six months.

By the age of 43, this rate is thought to drop to on to three per cent per month.

In order to boost your chances, Dr. Poliness recommends couples under 35 who have been struggling to get pregnant for 12 months should seek help from a fertility specialist.

Those over 35 who have been trying for six months should also seek help.