01

Yes, pregnancy is still possible

Perimenopause is the transition phase before menopause, typically beginning in your early-to-mid forties and lasting four to ten years. During this window, ovarian function declines, but it does not switch off. Cycles become irregular, ovulation becomes erratic, and periods may stop for months and then return.

The clinical definition of menopause is 12 consecutive months without a period. Until that point, you are still potentially fertile. Even an "anovulatory cycle" (a cycle without ovulation) can be followed by an ovulatory one without warning.²

The data backs this up. In Australia, around 1 in 100 women aged 45–49 still becomes pregnant naturally each year, and the rate climbs significantly higher in women who are sexually active and not using contraception.³

02

How fertility actually changes

Female fertility is mostly determined by egg quantity and egg quality, both of which decline through your thirties and forties.

Egg quantity

You are born with around 1–2 million eggs. By puberty, that drops to about 300,000. By age 37, fewer than 25,000 remain. By age 51 (the average age of menopause in Australia), fewer than 1,000.⁴ The decline accelerates from the late thirties onwards.

Egg quality

Quality declines faster than quantity. Eggs are more likely to carry chromosomal abnormalities with age, which is why miscarriage rates rise from around 20% at age 35 to over 50% at age 45.⁵

What this means in practice

• At 40, your monthly chance of pregnancy with one cycle of unprotected sex is around 5–10%.
• At 45, that drops to 1–3%.
• At 50, spontaneous pregnancy is rare but not impossible, and pregnancy after a long stretch of no periods has been documented.⁶

Fertility falls steeply but does not become zero until ovulation stops permanently.

03

Why fertility tests can mislead

Many women in their forties are told their FSH (follicle-stimulating hormone) or AMH (anti-Müllerian hormone) levels show they are "in menopause" or "no longer fertile". Both tests are unreliable as predictors of fertility in this window.⁷

FSH

FSH fluctuates wildly through perimenopause. A high reading one month can be followed by a normal reading the next. Even consistently elevated FSH does not rule out occasional ovulation.

AMH

AMH gives a reasonable estimate of ovarian reserve but it does not predict whether you will ovulate this month or next, and it cannot reliably distinguish "very low fertility" from "no fertility".

The honest summary: there is no single blood test that tells you in perimenopause whether you can or cannot still get pregnant. The only reliable indicator is 12 consecutive months without a period, with no other cause (such as MHT, hormonal contraception, or hysterectomy).

04

Contraception that actually fits

If you do not want to get pregnant, you need contraception until you have been period-free for the time periods below.⁸

How long to keep using contraception

• Under 50: continue contraception for two years after your last period
• 50 and over: continue contraception for one year after your last period
• If you are on hormonal contraception that masks your periods (Mirena, pill, implant, depot injection): periods are not a reliable marker. Talk to your GP about timing based on age.

Options that work well in midlife

• Mirena (hormonal IUD): highly effective, low maintenance, can be left in place during MHT for endometrial protection, treats heavy perimenopausal bleeding as a side benefit
• Copper IUD: non-hormonal, effective for up to 10 years, useful if you want to avoid hormones; may worsen heavy bleeding so not ideal if that is already a problem
• Progestogen-only pill (mini-pill): safe across the perimenopausal age range; needs daily timing
• Implant (Implanon): highly effective, three years per insertion
• Condoms: useful as backup or for STI protection; not high enough efficacy alone for most women who definitely do not want pregnancy
• Combined oral contraceptive pill: usually NOT recommended over 50 due to clot and cardiovascular risk; sometimes continued in healthy non-smokers under 50

What does not work as reliably in perimenopause

• Fertility awareness (cycle tracking): cycle length becomes unpredictable, so this method loses its accuracy
• Withdrawal: failure rates are 20%+ even in regular cycles, much higher when cycles are erratic

05

If you want to get pregnant

Spontaneous pregnancy is possible but increasingly difficult after age 42. The most useful steps:

• See a fertility specialist early. A GP referral in your early forties is much more useful than waiting until you have been trying for a year.
• Track ovulation actively. Ovulation predictor kits (LH strips) and basal body temperature charting are more useful than period tracking apps in erratic cycles.
• Understand the IVF picture. IVF success rates with your own eggs drop sharply after 40: around 20% live birth rate per cycle at 40, 5% by 43, and effectively zero by 45.⁹ Donor egg success rates remain reasonable into your late forties.
• Have the harder conversations. A fertility specialist can be honest with you about whether donor eggs, embryo adoption, or other paths are realistic for your situation.

06

When you can safely stop contraception

You can safely stop contraception when:

• You are over 55 (universally accepted upper limit for needing contraception)
• You are under 50 and have been period-free for two years (no MHT, no hormonal contraception masking your cycle)
• You are 50 or over and have been period-free for one year (same caveats)
• You have had a confirmed surgical menopause

If you are on a hormonal contraceptive that masks your periods and you are approaching the upper age limits, ask your GP whether stopping it and using non-hormonal contraception briefly will give a clearer picture.

Own Your Menopause Appointment: 5 Tips from a GP walks through how to prepare so the conversation is productive.

07

Why guessing is the wrong move

Pregnancy in your forties is the highest-risk category for both mother and baby. Rates of miscarriage, gestational diabetes, pre-eclampsia, placental complications, stillbirth, and chromosomal abnormalities all rise significantly.¹⁰ For women who unequivocally do not want a pregnancy, the cost of "assuming you can't" is much higher than the cost of using one of the contraceptive methods above.

The flip side is that women who do want a pregnancy in perimenopause are usually told they have less time than they actually do, or more time than they actually do, depending on which doctor they happen to see. Both errors are common. An honest fertility assessment with a specialist before age 42, when meaningful options still exist, is the most useful single step.

Either way, the principle is the same: do not assume your fertility is one thing or the other based on guessing. Find out, and plan from there.