Is a late period in your 40s pregnancy or perimenopause?

It can be either, and a pregnancy test is the only quick way to tell. The NHS lists both being pregnant and the start of menopause (perimenopause), usually between the ages of 45 and 55, among the common causes of a missed or late period. It says one of the first signs of perimenopause is usually a change to your periods: they may come more or less often, and bleeding may get heavier or lighter. In the US, the American College of Obstetricians and Gynecologists (ACOG) puts the average age of the last period at 51.

Why pregnancy and perimenopause symptoms overlap

Several symptoms appear on the NHS lists for both, and none rules the other out.

Symptom	Early pregnancy (NHS)	Perimenopause (NHS)
Periods	A missed period	More or less often, heavier or lighter, then stopping
Tiredness and sleep	Extremely tired after usual activities	Sleep problems, sometimes with night sweats
Mood	Changes in mood	Mood swings, low mood, memory problems
Peeing	More often, without pain	More often, including at night
Feeling sick	Any time of day or night	Not listed
Breasts	Larger and tender	Not listed
Hot flushes and night sweats	Not on the early-signs list	Listed
Vaginal changes	More discharge	Dryness, burning or itching
Weight	Not on the early-signs list	Gain, often around the stomach

Nausea, tender breasts and a metallic taste lean towards pregnancy; hot flushes and vaginal dryness lean towards perimenopause. For the premenstrual version of this comparison, see PMS or pregnancy symptoms.

Can you get pregnant during perimenopause?

Yes. The NHS says: "It's possible to get pregnant during perimenopause." ACOG explains why: "Some months, the ovaries may release an egg. Other months, they do not release an egg."

The UK Faculty of Sexual and Reproductive Healthcare (FSRH), in its guideline on contraception for women over 40, describes perimenopausal cycles as erratic, with spells of both ovulatory and anovulatory cycles. An early change is shorter cycles, before they lengthen and stop, and anovulatory cycles are characteristically 6 to 8 weeks long with heavier, longer bleeding.

Fertility is lower, not gone. The FSRH guideline cites reviews putting the chance of pregnancy over a year of unprotected sex at around 10 to 20% for women aged 40 to 44 and closer to 12% at 45 to 49, and says spontaneous pregnancy is rare after 50. It notes that women over 40 have unintended pregnancies too: in 2015, 28.1% of recorded pregnancies in women aged 40 and over in England and Wales ended in abortion.

Hoping to conceive? See trying to conceive at 40, chances of conceiving by age and irregular periods and conceiving; if your periods stopped before 45, early menopause and conceiving.

Which tests help, and which do not

A pregnancy test

This comes first. If you do not know when your period is due, the NHS says to test at least 21 days after you last had unprotected sex. A positive result is almost certainly correct. If a test is negative and you still think you might be pregnant, wait a few days and test again, and see your GP if a second test is negative and your period has not arrived. Pregnancy symptoms but a negative test covers false negatives.

Menopause tests

Usually none is needed. NICE guideline NG23 says that in people aged 45 or over, perimenopause should be identified without laboratory tests, from recently started vasomotor symptoms (hot flushes and night sweats) plus any change in the menstrual cycle. It suggests considering a follicle-stimulating hormone (FSH) blood test only at 40 to 45 with symptoms including a cycle change, or under 40 if menopause is suspected, and not in people using combined hormonal contraception or high-dose progestogen.

A hormone result does not answer the pregnancy question either. The FSRH says that during perimenopause, isolated oestradiol, FSH and LH levels "can be misleading and should not be used as the basis for advice about stopping contraception; ovulation may still occur with a risk of pregnancy". At-home fertility tests explains the limits of hormone kits.

When can you stop contraception in perimenopause?

UK guidance from the NHS and the FSRH is based on your last natural period:

Last period at 40 to 49: keep using contraception for 2 years after it.
Last period at 50 or over: keep using it for 1 year after it.
At 55: the FSRH says all women can stop, as spontaneous conception after this age is exceptionally rare even if you still have some bleeding.

The NHS says hormonal contraception can make it harder to tell if you have reached perimenopause or menopause: the progestogen-only pill, hormonal coil, implant and injection can make periods irregular or stop them, and the combined pill causes monthly bleeds for as long as you take it. The combined pill is not recommended from 50. HRT is not contraception: the FSRH says contraception should continue alongside sequential HRT while you are perimenopausal or your status is uncertain.

When to see a GP

Possible ectopic pregnancy. The FSRH notes that women over 40 are nearly three times as likely to have an ectopic pregnancy as younger women, though the overall risk is still very low. The NHS says to contact your GP or call NHS 111 if you might be pregnant and have a combination of symptoms such as tummy pain low down on one side, bleeding that starts and stops or is watery and dark brown, shoulder tip pain, or discomfort when you poo or pee, even without a positive test.
Emergency. Call your local emergency number (999 in the UK and Ireland, 911 in the US and Canada, 000 in Australia, or 111 in New Zealand) for a combination of sharp, sudden and intense tummy pain, feeling very dizzy or fainting, and feeling sick.
Bleeding changes. The NHS says to contact your GP if you are bleeding more, not less, than before, or have any bleeding after 12 months without a period. ACOG says bleeding or spotting between periods or after sex is not normal.
Missed periods. See a GP if you have missed 3 periods in a row, or a missed period comes with weight change, tiredness, facial hair growth, or dry or oily skin.

Frequently asked questions

Can you get pregnant during perimenopause without having a period?

Yes. ACOG explains that ovulation happens mid-cycle and a period follows about 2 weeks later if you are not pregnant, so an egg can be released after a long gap with no bleeding. The NHS only counts menopause after 12 months without a period. If you are late and have had unprotected sex, test.

Can you get pregnant during perimenopause on HRT?

Yes, if you are still ovulating. The FSRH guideline says HRT is not a contraceptive method and that contraception should continue alongside sequential HRT while you are perimenopausal or your status is uncertain. It also notes that perimenopausal women on sequential HRT usually keep having regular withdrawal bleeds, so those bleeds say nothing about fertility.

What are the chances of getting pregnant during perimenopause?

Lower than earlier in life, but real. The FSRH guideline cites reviews putting the chance of pregnancy over a year of unprotected sex at around 10 to 20% at ages 40 to 44 and closer to 12% at 45 to 49. It says spontaneous pregnancy is rare after 50 and exceptionally rare after 55.

Is nausea a sign of pregnancy or perimenopause?

Feeling or being sick is an NHS early pregnancy sign but is not on its list of perimenopause symptoms, so nausea with a late period leans towards pregnancy. It is not proof on its own. A pregnancy test answers it; if the test is negative and the nausea carries on, see your GP.

Is spotting a sign of pregnancy or perimenopause?

It can be either. The NHS lists a very light bleed around the time a period is due among early pregnancy signs, and irregular, lighter or heavier bleeding in perimenopause. ACOG says bleeding or spotting between periods or after sex is not normal. Take a pregnancy test first, then ask your GP about the bleeding pattern.

Pregnant or Perimenopause? A Late Period in Your 40s