How many weeks pregnant am I?
Pregnancy dates can feel confusing because the count starts before you actually become pregnant. We’ll explain your periods, help you identify the first day of your last normal period, and then estimate how many weeks pregnant you may be.
Not everyone has a 28-day cycle.
A menstrual cycle is counted from the first day of one period to the first day of the next. Cycle length varies from person to person, and even the same person may have some variation from month to month.
Day 1
The first day of your normal menstrual bleeding is Day 1 of the cycle.
Egg release varies
Ovulation means an egg is released from an ovary. It does not always happen on Day 14.
Regular cycles help
Using your last period to estimate pregnancy dates works best when your periods are fairly regular.
Why pregnancy seems “two weeks older”
Pregnancy is counted from the first day of your last period, even though you were not pregnant yet. Fertilisation means a sperm joins an egg. This often happens about two weeks later. That is why “6 weeks pregnant” often means the pregnancy began developing about 4 weeks ago.
Which date should I use?
Use the first day of your last normal period. Healthcare workers may call this your LMP. It is the first day you had the type of bleeding you would recognise as your usual period — not the day it ended.
Normal period
Bleeding that looks and lasts like your usual period. Use its first day.
Spotting
A few spots of pink, red or brown blood, or bleeding much lighter than your normal period, may not represent a true menstrual period.
Unusual light bleed
If the “period” was much shorter or lighter than usual, tell your doctor or nurse that you are unsure.
Light spotting can happen early in pregnancy, but bleeding alone cannot tell you why it happened. If it was unusual for you, mark your dates as uncertain.
Select the first day of your last normal period.
We’ll calculate an estimate from the date you choose. This does not replace a clinical assessment or an ultrasound when your dates are uncertain.
What is happening at this stage?
What does the pregnancy look like this early?
Development is gradual. The medical terms also change with time. These descriptions are intended to give you factual context, not to tell you how you should feel about your pregnancy.
Pregnancy dating has started, but conception usually has not.
These first two weeks are included because pregnancy is counted from the first day of your last period.
The pregnancy may begin.
A sperm may join an egg. The growing group of cells may then attach inside the womb.
Embryonic development is underway.
Tissue continues to grow. It will soon be organs.
Doctors call it an embryo at this stage.
Early parts of the organs continue to develop. The pregnancy count is still about two weeks ahead of the time since the sperm joined the egg.
The fetal stage begins.
The medical term changes from embryo to fetus as growth and development continue.
Sometimes an ultrasound is the better way to date a pregnancy.
Using your last period gives an estimate. A doctor may recommend an ultrasound when you cannot remember the date, your periods are irregular, that bleeding was unusual, or your symptoms and dates do not fit together.
Don't guess if you aren't sure.
It is okay not to know the date. Tell your doctor or nurse that you are unsure rather than choosing a date just to complete the form.
A date calculator cannot show where the pregnancy is growing.
An ectopic pregnancy grows outside the womb and can be dangerous. A calculator cannot detect it. Get urgent medical care if you may be pregnant and have any of the symptoms below.
- severe or worsening abdominal or pelvic pain
- significant pain mainly on one side
- fainting, collapse or severe dizziness
- heavy vaginal bleeding
- shoulder-tip pain with abdominal pain or feeling faint
- feeling severely unwell