If your first baby was conceived with no more planning than a romantic dinner à deux, some saucy knickers and a drunken rumple under the bedsheets, it can be perplexing when getting pregnant again proves difficult, if not impossible. After all, your offspring is living testimony to your fertility, so what’s the problem?

Unfortunately, past fertility does not equal future success. Some doctors believe that secondary infertility – the medical term for being unable to conceive when you have given birth before – is increasing and affects as many as one couple in five. An American study last year suggested that it is more common than primary infertility, in part because the age at which women have their second child is rising. Official government statistics for 2006 show that the mean age for mothers having their first child was 27.6 and 30 for the second.

Dr Raj Mathur, a fertility consultant at Addenbrooke’s hospital in Cambridge, says: “Infertility generally is increasing and we see lots of cases of secondary infertility, particularly as women delay motherhood. Although they may conceive their first child quickly, by the time they get around to their second their fertility levels may have dropped dramatically.”

Sometimes the ease of a previous conception has masked an existing health problem, such as poor sperm count or polycystic ovaries. Problems may be caused by a difficult previous pregnancy or delivery (see panel for more information). Dr Mathur says: “There’s controversial research which suggests that women who have had Caesarean deliveries take longer to conceive, perhaps because of scarring.”

Fertility issues are often wrongly assumed to be a “woman’s problem”, but in a third of cases the difficulty lies with the man. And while famous senior dads such as Des O’Connor (who was 72 when he had his fifth child) and Sir Paul McCartney (a sprightly 62) give the impression that there is no barrier to male fertility, research suggests that sperm quality and quantity decline from 35 onwards.

Sperm counts can be affected through trauma, say from an ill-placed rugby tackle, but also by sexually transmitted diseases such as gonorrhoea or chlamydia. It is well-known that the latter infection – the UK’s most common STD – damages female fertility, but a Spanish study presented last month at an American Society for Reproductive Medicine conference, showed that it also affects sperm concentration, motility and shape.

Lifestyle is also important. Before trying for baby No 1 many parents may have consumed Popeye-like amounts of spinach, watched their weight and forsaken alcohol and cigarettes. Second-time around, complacency may have snuck in. Cases of secondary infertility are officially bracketed under general infertility, so there are no specific figures available. But the fertility expert Zita West is seeing more incidences at her London clinics.

She says: “It takes on average six months to conceive, but add to that the tiredness and stress of being a parent and it can take longer. Some women may have just stopped breast-feeding, so their cycles are all over the place, while others simply aren’t having enough sex.”

‘Couples feel they shouldn’t complain’

Any fertility problem is stressful – sufferers say it can take over everything – but with secondary infertility there is less support available. Family life has to go on and most help groups concentrate on the childless. Susan Seenan, of Infertility Network UK, says: “Couples may feel they don’t have the right to complain, but that doesn’t remove the feeling of incompleteness.”

Figures from the Government’s National Statistics agency show that the number of only-child families is increasing. While 15 per cent of women born in 1960 had only one child, this increased to 19 per cent for those born in 1970. The most common age gap between children is two to four years, but how do parents know if time is on their side? The short answer is that there are no rules when predicting fertility. Laurence Shaw, the deputy medical director of the Bridge Fertility Centre in London, says: “Two women of the same age and weight with similar lifestyles and medical histories could have completely different biological ages.”

But there are warning signs. If your periods are irregular and sexual intercourse painful, you may have an infection or ovulatory problem. A common condition such as polycystic ovaries, which hinders ovulation, can be triggered by excessive weight gain in pregnancy.

Diabetes and raised blood pressure can affect fertility, as can cancer treatments. And then there’s early menopause. If your mother had an early menopause, you might too. Shaw advises that this is not clear: “Nobody has discovered a gene for the timing of menopause yet.”

If you are over 35 and conception is taking more than six months, the official advice is to seek medical help quickly. Some problems are easily treated, but for others IVF is the only answer (although there is no public funding for those who already have children) and success rates plummet with age, from 28 per cent in the under35s to 10 per cent in women aged 40 to 42. The good news is that couples with secondary infertility are more likely to achieve a second pregnancy, even with fertility treatment.

Shaw says: “For the majority of people who have had one baby, conceiving the second won’t be a problem. But as time passes the unexpected occasionally happens – fibroids, declining fertility or endometriosis. John Lennon had it right when he said ‘life is what happens to you while you are busy making other plans’.”

CASE STORY: JODIE OLIVER: 'I COULDN’T HAVE MY SECOND CHILD BECAUSE OF POLYCYSTIC OVARIES'

Jodie Oliver (pictured above with her daughter), became pregnant with Evelyn, 2, when she was 31 after coming off the Pill just three months earlier. She presumed that her next child would be as easily conceived, but after 18 months of trying, Jodie and her husband, Paul, have been told that it will be difficult for them to have another child naturally.

Jodie, now aged 34, was told by doctors that she had polycystic ovary syndrome, possibly triggered by her weight gain in pregnancy. But even if she had been regularly ovulating, a test showed that Paul’s sperm were abnormally shaped and unable to penetrate eggs.

Armed with this new knowledge, the Olivers were surprised that they managed to conceive Evelyn at all, let alone with such ease.

Jodie, who works in a doctor’s surgery in Sussex, says: “It has been surreal. How can we be infertile when we’re parents? We feel utterly blessed with our daughter, but we can’t understand why we can’t do it again.

“Perhaps I don’t have the right to complain as I know the joy of someone shouting ‘Mummy’. But then the other part of me thinks this is harder than primary infertility because I know how fantastic being a mum is and I want to do it again.”

CAUSES OF INFERTILITY

How to test for problems
The treatment of secondary infertility is similar to primary infertility. Couples should be tested to check the woman is ovulating properly and that the man’s sperm is normal. In older women, causes break down into difficulties in an earlier pregnancy or delivery, or an existing but previously undiagnosed health condition.

Pregnancy or delivery problems
A womb infection, heavy bleeding after a Caesarean or the retention of part of the placenta in the womb after delivery can all cause scarring, making it harder for embryos to implant. About 1 per cent of pregnancies are ectopic, when the fertilised egg implants outside the womb, and about a third of women who have suffered will find it difficult to become pregnant again.

Underlying health problems
Pelvic inflammatory disease – often associated with STDs – can cause infertility if left untreated. In extreme cases of endometriosis, a condition in which the cells that normally line the womb are found elsewhere in the body, scarring can make conception difficult. In mild to moderate cases, studies found that removing endometriotic spots improved the chances of conception for women under 40 by up to 75 per cent.

Ovulatory problems
Up to a third of infertile couples are affected by an ovulatory disorder, typically polycystic ovaries. About one woman in five has polycystic ovary syndrome, but only a small proportion will develop fertility problems. If fibroids are too large or in a difficult position, they can prevent embryos from implanting.

For help, support and information: www.fertilityzone.co.uk | www.fertilityfriends.co.uk | www.infertilitynetworkuk.com

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