Unless you are actively trying to get conceive a child, nothing can induce panic more than a late period.
A zillion scenarios run through your mind. Are you pregnant? And, if you are, are you even ready to be a mum yet?
It's also a panic which doesn't necessarily die down with age.
But relax - or at least try to. Because a late period doesn't necessarily signal the patter of tiny feet.
There are several factors which can delay a period - and here they are.
1. Early menopause
Perhaps not the cheeriest one to kick off with, but as Glamour reports, around one in 100 women will experience early menopause before they reach the age of 40.
It's worth visiting your GP if your periods have disappeared or if they're becoming increasingly sporadic.
If you're suffering from hot flushes, night sweats, irregular sleep or vaginal dryness in conjunction with late periods, you should also seek medical advice.
2. Being stressed
This seems to be the Dark Overlord of health woes, manifesting itself in hair loss, sleepless nights, problem skin and fluctuating weight, to name a few.
It can also play havoc with our periods.
This is because the part of our brains which produces hormones crucial to reproduction responds to stress badly, skewing the hormone production.
So a person's periods will therefore become irregular - even stop altogether - unless they manage to tackle their stress.
3. Being on medication
There are certain types of medication which signal to your body to stop menstruating.
Your cycle may be impacted by some antibiotics, contraceptive pills and antidepressants disrupting your hormone levels.
It's therefore important to talk to your GP about possible side-effects of any course of medication you're about to embark on.
4. Too much exercise
This will only apply if you're training for something which involves extreme endurance and fitness, like a marathon or triathlon.
Not so much if you enjoy the odd jog of an evening.
When training, your body has a response to when it feels it's using up too much energy, and this is to deactivate any functions it doesn't see as necessary.
One of these may be your periods. The good news is, should you ease up on your regime, your periods should resume.
We know the symptoms of early menopause can manifest themselves when we sleep.
But our sleep patterns themselves can have a knock-on effect on our periods.
For example, if you travel and change time zones dramatically, this can cause your periods to go off-kilter. Similarly if you work shifts.
6. Changing weight
It's not so much case of you shedding a couple of pounds, more if you lose - or gain - a significant amount of weight.
This is because your body requires a certain amount of body fat to ovulate so any sudden weight loss will stop your period.
The same applies if you put a lot of weight on over a short space of time, the increase in fat cells raise oestrogen levels which will stop your body from releasing an egg and therefore miss a period.