Why Haven't You Started Your Period Yet?

Primary amenorrhoea is the failure of your first menstrual period (menarche) to arrive. It is normal for girls to start their periods between ages nine and 12.

When menstruation doesn’t arrive at the same time as everyone else, it might mean something isn’t quite right – but there’s no need to panic before seeing a doctor for assessment. Typically there is no need to worry before age 15-16 – some of us are just a little later to the party (some might say fashionably late!).

Sometimes other signs of puberty may be missing as well (underarm hair, pubic hair, growth of labia, etc.), in which case this should be discussed with a doctor sooner. The absence of puberty may mean something more serious is occurring.

The absence of a menstrual period after age 15-16 means something may also be going wrong somewhere along the line. Sometimes these things can be serious, like a missing uterus, or they could be more manageable, like being underweight.

If you’re concerned, talk to your healthcare provider.

Reasons your period may not arrive

There are a handful of causes, and they all have quite different implications.

Low body fat – those with low body fat don’t have the required percentage of fat cells required for sufficient oestrogenic hormone production
Over-exercising
The hymen completely covers the vaginal opening so no blood can exit the vagina (an imperforate hymen)
A blockage or narrowing of the cervix (cervical stenosis), causing blood to back up in the uterus
A transverse vaginal septum that blocks flow of blood out of the vagina
The vagina, uterus or cervix are missing (vaginal agenesis, uterine/Mullerian agenesis, cervical agenesis)
The vagina, uterus, or cervix are not properly formed (vaginal hypoplasia, uterine hypoplasia, cervical hypoplasia)
The ovaries aren’t functioning correctly – possibly due to tumours or hormone dysregulation – no ovulation generally means no period
The areas that deal with hormones are not functioning optimally (hypothalamus, pituitary, thyroid, adrenals) – dysfunctional hormones means no ovulation/disrupted hormone cascade
Unknown causes
Pregnancy
Genetic conditions such as Kallmann syndrome or anatomical abnormalities caused by genetic defects

As you can see, there is quite a range of reasons why you might not have your period yet. So next is an appointment with your doctor to find out why.

Also check out secondary amenorrhoea, since some of these like over-exercising and low weight are covered in more detail there.

What the doctor might discover

Underlying illness – cystic fibrosis, heart problems, chronic illness
A genetic blip that has resulted in you growing differently in the womb (see DSD for more information)
Poor nutrition and low weight (possibly linked with disordered eating or illness)
Tumours

A physical examination will be done, with questions regarding your medical history. A pregnancy test will be done.

Blood tests may include a range of hormone tests, including oestrogen and thyroid hormones. Imaging scans may be taken to establish what lies beneath your flesh in your pelvis – if you are missing organs or even have duplicates.

Treatment and management of primary amenorrhoea

Treatment depends entirely on why the cause, so see the separate sections for each topic for more information. Seek advice from your healthcare practitioner.

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