Thousands of Kiwi couples will have their baby plans dashed this year as they discover they can't conceive naturally.
Holding their child and watching them grow up will become a dream out of reach for one in four women who try - unless they choose to get assistance.
Infertility is defined as not conceiving after 12 months of trying.
The trend is rising - five years ago, one in six women experienced problems, support organisation Fertility NZ figures show.
There are about 5000 first-time fertility clinic appointments every year.
Fertility Week, which starts today and is run by charity Fertility NZ, aims to raise awareness around what it takes to have a child.
It turns out, Kiwis aren't very aware. Around 85 per cent of women can't identify their fertile window and people are underestimating what effect age has on fertility, according to research by Dr Antoinette Righarts from the University of Otago.
The main factor in increasing infertility is couples are choosing to have children later in life, Fertility Associates' Auckland medical director Dr Simon Kelly explained.
• Making Babies: A Herald series on infertility
• Today: NZ's fertility situation
• Tomorrow: Making babies with help (IVF, AI etc)
• Friday: The last chance (surrogacy or donor egg or sperm)
"Women are expected to have a career now and a family. It's just the way it is. There are no signs this is going to change."
In 1970, the median age a woman had her first child was 23, in 2016 it was 29, Statistics NZ reported.
Kelly urged couples to plan for their last child and not their first. For a 90 per cent success rate to have three children naturally, a woman needs to start trying at 23, the Oxford journal Human Reproduction found.
If they want two children, the woman should start trying at 27, and if they want one for a 90 per cent success rate, they should try no later than 32.
"If someone has a plan about what their ideal family size is, then take into account when you start trying," Kelly said.
"Say if someone starts at 35 with a view that they want three children. If they have one at 35, by the time they've had that baby and are thinking about number two they could potentially be 37 - the chance of conceiving may be reduced and you might need treatment.
"If they are successful by the time they're ready for number three they could easily be in their 40s."
Increasing obesity could also be a factor in rising infertility. New Zealand is now the third fattest country in the world according to an OECD obesity update, released this year. One in three Kiwis was found to be obese.
Juanita Copeland, 40, had her daughter after five years of trying. She started at age 30 and went through five rounds of IVF and two frozen embryo transfers to the tune of $50,000. Her husband's vasectomy reversal had been unsuccessful and she had some unexplained infertility.
Copeland knows how lonely the infertility journey is. The Fertility NZ executive committee member encouraged Kiwis to be aware of their fertile window and contact their GP if they have any concerns - as IVF is not a silver bullet.
Her heart breaks when she hears people say "I thought we had heaps of time but we left it too late".
"There is nothing worse than buying a house you want to fill with children and finding out you left it too late.
"It's an incredibly harrowing thing to happen. It is life-changing. You just feel so powerless. You want something so, so, so badly and you feel like you're doing everything right. It's very hard for couples to articulate."
People can be fixated on the "Kiwi dream" that life has to happen in a certain order - house, marriage, baby - Copeland said. But prioritising children may save you grief later down the track.
Fertility declines sharply for women from age 35. But men and women are equally to blame for fertility issues.
Infertility is 30 per cent due to the man, 30 per cent due to the female, 30 per cent to both and 10 per cent unexplained.
An international study found sperm counts have dropped by more than 50 per cent in less than 40 years among men in Western countries - including New Zealand.
Some studies show a reduction from age 40 in men for couples trying to become pregnant naturally, and from 50 when using IVF.
Common medical conditions which reduce the chance of having a baby naturally are polycystic ovarian syndrome, endometriosis and male factor infertility.
The stress of fertility issues can break relationships, Copeland said. And when men discover they are the reason the couple can't conceive they take it very personally.
"[Male infertility] can be almost harder for a couple to deal with. For men fertility is connected with sexuality and a sense of manhood and men are less likely to talk about it.
"Women tend to be fixers, they say 'I wish it was my fault then I'd take all the Chinese herbs and do everything'. Generally speaking, men are not as proactive but take it really personally. Those couples are under quite a lot of strain."
• Women should learn their mother's age at menopause: if earlier than the average of 52, seek advice earlier.
• Get tested - concerned women can get an Anti-Mullerian Hormone test which indicates the ovarian reserve of eggs and men can get their sperm tested for quality, movement and quantity.
• Too little or too much exercise can impair fertility for women and men.
• Maturation of egg and sperm takes 100-120 days, so your lifestyle within that time may impact chance of conception, the health of the pregnancy, baby and child. A healthy diet, normal weight and low-stress lifestyle is best. Also quit smoking and reduce caffeine and alcohol for optimum chances.
• Plan for your last baby, not your first.
• Seek help from your GP after 12 months of trying to conceive, or nine months if the woman is over 35 and six months if the woman is over 40.
• Start taking folic acid before conception as it reduces the risk of birth defects like spina bifida.
Pregnancy is only possible six days out of a woman's entire cycle. This is the day of ovulation and the five days immediately prior.
Ovulation is where an egg is released by one of the ovaries into a fallopian tube. It has a lifespan of 24 hours to be fertilised by sperm or it will disintegrate.
Sperm are able to survive for up to five days after intercourse so any sex within five days of ovulation could result in a pregnancy. But the closer to ovulation sex takes place, the higher the likelihood of conception will be.
If a woman has sex six or more days before she ovulates, the chance she will get pregnant is virtually zero. If she has sex five days before she ovulates, her probability of pregnancy is about 10 per cent, the Victorian Assisted Reproductive Treatment Authority reported.
The probability of pregnancy rises steadily until the two days before and including the day of ovulation.
At the end of the "fertile window", the probability of pregnancy declines rapidly and by 12-24 hours after she ovulates, a woman is no longer able to get pregnant during that cycle.
For those women who are not aware of their fertile window, sex is recommended every two to three days to help optimise their chance of conceiving.
Ovulation is when a mature egg is released from the ovary, moves down the fallopian tube, and is available in the fallopian tube to be fertilised.
Work out the length of your average menstrual cycle. Day one is the first day of the menstrual period and the last day is the day before the next period begins.
Ovulation happens about two weeks before the next expected period. So if your average menstrual cycle is 28 days, you ovulate around day 14.
Women can tell they're ovulating by a slight rise in their temperature and a change in their discharge to a clear, slick mucus.
Fertility NZ is a charity dedicated to supporting all people who face infertility challenges. Find out more about fertility week here.
It took four rounds of IVF, four years and $60,000 for a Wellington couple to conceive - then they found out they were having twins.
Jennah Rasmussen and Marc Wright thought they had heaps of time to have a baby when they met aged 28 and 38. Wright had already had five children and Rasmussen thought she'd start trying for a family in her 30s.
But it didn't happen easily - a journey that has prompted Rasmussen, now aged 36, to share what she wished she had known for Fertility Week.
Four years after they met they had bought a house and got married. It was time to start trying. But after eight months nothing had happened.
Testing found Rasmussen had very low Anti-Mullerian hormone levels, a test for remaining egg supply, and Wright had virtually no sperm.
He had had a vasectomy aged 28 and then had it reversed 15 years later, but not enough sperm could get through. Chances of pregnancy are decreased as the time between getting a vasectomy and a reversal is increased.
Rasmussen discovered her mum had gone through early menopause which is genetic.
"If I knew what I do now in my 20s I would have done it differently and sooner. You might think you're okay but you just don't know.
"I wanted to get married first then have children. There was a natural progression in my head.
"But now, I would have sped up on the baby-making and put the wedding on hold."
The couple embarked on their first round of IVF in 2014. They privately funded it to avoid the long wait.
Rasmussen thought they'd breeze through and end up with a baby at the end of it. But they only got five eggs and just one embryo survived to five days. It did not take when it was implanted in Rasmussen.
"That whole cycle was heartbreaking. I thought I'd get 20 eggs, they'd all work and I'd have a backup family in a test tube."
After two more failed rounds the doctor suggested donor eggs. Rasmussen's sisters tested their AMH levels in case. One sister had poor levels like Rasmussen, but the other sister who is seven years older had better levels. It shows that you can never be sure, Rasmussen said.
They had already paid for another round of IVF so decided to try that before resorting to donor eggs. The two transplanted embryos were successful and they were pregnant with twins. Rasmussen is currently 21 weeks pregnant.
"After that massive long journey thinking it's never going to happen and contemplating life without children, it's a dream come true.
"We're just very thankful for modern science. Lots of people tell you maybe it's time for you to give up or look at other options. But you have to know when you'd be happy to stop because you're the one who will have regrets if you do."
Rasmussen advises to get your AMH and sperm count tested, even if you don't think anything is wrong. Don't leave it as late as she did and learn your family history.
A sex educator has answers on the ins-and-outs of sexual intercourse.