One is enough? For women with secondary infertility, it might not be a decision they get to make.

One is enough? For women with secondary infertility, it might not be a decision they get to make.

During the 2½ years that my husband and I tried unsuccessfully to fall pregnant with our second child, we turned to close friends and family for comfort. Their consolations usually went something like this: "Well, at least you have one child. Lots of people don't even have that."

They were absolutely right. We were incredibly lucky to have our beautiful, healthy daughter, and 2½ years of trying wasn't very long in the scheme of things. But still, it was a difficult time. What upset us most about the prospect of not having another child was the thought that we might be unable to provide our daughter with a brother or sister.

It's been very hard to deal with, yet often you can't admit that, because you feel really selfish that you already have one beautiful, healthy child 

When a couple has had one successful pregnancy, who can blame them for hoping to do it all again? But it's this expectation that intensifies a couple's struggle when they're faced with problems conceiving, or maintaining, another pregnancy.

The rising age of first-time parents means that more of them are encountering problems when they try to "go again" – a condition called "secondary infertility".

"The average age at the birth of the first child for Australian women has been rising by two years per decade over the past 50 years," says Sydney fertility specialist Dr Katrina Rowan. "It follows that couples will be older when having subsequent children, and therefore secondary infertility is expected to rise.

"Often, subtle problems with fertility can be overcome when couples are young, but with increasing age, the eggs and sperm can be poorer quality."

Most people mistakenly assume that fertility doesn't change, says Liz Hurrell, fertility counsellor at Sydney's Royal Prince Alfred Hospital. "Couples often have an expectation of the sort of family they hope to create, and when they're challenged by something beyond their control they have a sense of loss," she says. "For many couples it can feel very much like their life is on hold - 'will this happen for us or not?'"

Couples with secondary infertility don't get as much support from their families or other people in the community as people facing primary infertility, says Hurrell. "Couples dealing with it question their own sadness themselves. There's a sense of, 'I have a child, I am a parent, I should be happy.' It's almost as though you're being too selfish or want too much. But these couples aren't just yearning for a child; they want to have another child to enrich the life of the child they already have."

This paradox – between the happy feelings a couple have about their existing child, and their sense of sadness at not being able to have another – is at the heart of secondary infertility.

"There's a sort of irony there," Hurrell says. "Their knowledge of the joy of parenting underscores the pain of secondary infertility. These families are connected with the world of being parents – they're part of playgroups and other parenting communities – yet they're different from other members of that community. Many couples talk about it as a sense of isolation."

Julie Shinners and her husband, Dave, started trying for a family when she was 36 and he was 38. Julie fell pregnant at once. She had two miscarriages before falling pregnant again with her son, Hugh, now four. "Literally I would say 'Let's try again', and I knew I'd get pregnant," she says.

But after the birth of Hugh, everything changed; Julie couldn't fall pregnant as easily as she had before. "After about six months of trying, my obstetrician said he didn't really know what was going on, but advanced maternal age was definitely a factor."

The couple, from Toowoomba in Queensland, have all but given up on providing their son with a sibling. "I was so smug when I was falling pregnant all the time, and then after Hugh this whole other world of infertility opened up," she says, now aged 42.

"You just can't take anything for granted. It's been very hard to deal with, yet often you can't admit that, because you feel really selfish because you already have one beautiful, healthy child."

Melbourne fertility specialist Dr Kate Stern says people are mistaken in thinking IVF can fix age-related fertility. "IVF doesn't change your egg quality, and that is really what will determine your success," she explains.

Pre-existing conditions such as polycystic ovary syndrome (PCOS), endometriosis or fibroids can also cause problems the second time around, she says, as can weight gain. "The weight gained after you have a child may increase the chance of irregular ovulation, and therefore difficulties falling pregnant," Stern says.

Sydney fertility naturopath Amanda Haberecht says autoimmune antibodies can also affect fertility. "It's common for women to develop thyroid problems after pregnancy. They might experience weight gain, fatigue, low mood and longer menstrual cycles, and think it's all because they've just had a baby, when in fact it's their thyroid. This will absolutely impact on their ability to conceive again. Or they will start to miscarry."

Elevated levels of prolactin, the hormone that stimulates milk production in breastfeeding mothers, or scar tissue from surgical procedures such as dilatation and curettage (D&C) or caesarean sections, known as Asherman's syndrome, are other factors that can contribute to fertility problems, she says.

I fell pregnant with our son a few months after I had a surgical procedure for Asherman's syndrome. We'd almost come to terms with not having another child and had started looking into adoption. Four years later, we had a third child.

"In my experience, women who have struggled to conceive their first baby and then experience secondary infertility are much more philosophical about it, whereas women who didn't struggle to fall pregnant with their first child will have more difficulty [emotionally]," Haberecht says. "A lot of women I see feel so blessed at having had one pregnancy that they look at a second pregnancy as a total bonus."

This article first appeared in Sunday Life.