question about skipping periods
 

this is more of a Ladie's Lounge question, but from reading the rules i don't think i can post there. so i guess this is the next best place.

my girlfriend just recently skipped her last period, and we were freaking out because we thought she might have been pregnant. she took a pregnancy test and she tested negative so that was a relief.

but she says she has never in her 25 years of life has missed a period, and she doesn't know why. so can any ladies, or knowledgeful guys help us out as to why she missed that one?

Here are a few that come to mind immediately:

Stress.
Increased physical exhertion.
Significant loss of weight.
Lack of sleep.
Significant changes in routine.
Change in medication.
Absence of an alpha female that usually kept her hormones on track.
Pre-menopause.

This is rare, and probably isn't happening to your girlfriend, but one of my friends faced pre-menopause symptoms starting at age 22. It started off with a missed period, then another. She finally decided to go see a physician and was put on hormone birth control to regulate her system. Not sure how well that worked for her, haven't asked, but she hasn't had any children.

Did the next one happen exactly when it was supposed to, did she exactly skip a period, or did she have a way late one (2-3weeks)?

Pregnancy tests detect the hCG hormone in urine.

Hormones are measured in units called IU. A pregnancy test generally detects hCG at a level of 25 mIU/mL in urine.

In a normal healthy non-pregnant woman, the hormone is present at 5 mIU/mL in blood. When urine stays in the bladder overnight, it reaches a hormonal equilibrium with the blood, and so testing for hCG in urine can tell you the level in blood.

In a woman who has conceived, the level of hormone rises rapidly to about 20 mIU/mL by the day of a missed period, hitting 30-50 mIU/mL a few days after the missed period and climbing rapidly in the weeks after to a level of tens or hundreds of thousands.

If an embryo is formed by fertilisation, the hormone level starts to rise, it is possible for the embryo to not develop into a foetus, and for the pregnancy not to happen. This hormone spike is called "chemical pregnancy", and can result in missed periods, or even positive test results.

It is possible also for a test to give a false negative result - if the test is taken too early in the pregnancy, or if a sample is used that is too dilute (not first morning, or after something diuretic such as coffee has been taken).

If you doubt that the test result matches the case history, you should always take another test first thing in the morning after 2 days have passed.

it's actually only been a week so far, and she still hasn't had one.

she is going to take another preggers test tomorrow morning, thanks everyone.

It happens.

If she has low bodyweight to begin with it's more likely to happen.

If she was sick recently, that can be enough to throw things off.

Sometimes diet can impact it.

Either way, nothing too much to worry about for a single missed incident. If it happens more than once, or especially two or more concurrent periods missed, then it's time for a doctor's appointment.

Heck, she should probably go the doctor anyway. It's always good practice, pun not intended.