What reasons besides pregnancy and stress could cause one's period to be constantly very late?

"After one month of trying I became pregnant and had a beautiful healthy boy!"

"After over 7 years of trying to conceive and thousands of dollars spent on infertility treatments, I had actually succeeded to get pregnant the natural way without any drugs or medical intervention "

" I just wanted to say thank you for writing this program and for giving hope to women at my age. I am 46 and I am finally going to be a mother."
Best information and tips about help for pregnant women, help with pregnancy and pregnancy help
This is the 3rd time since July of last year that my period has been over a month late? I keep taking pregnancy tests but they’re all negative. What else could be causing such a late period?

There are a few things that could cause "late" periods.
(sorry if I may be repeating what others have answered)
1) When a girl starts to menstruate for the first time, it may take up to a year before it becomes "regular" and that may not mean 28 days. Some women are regular with 3 months intervals between periods. This can happen again when beginning or going off hormonal contraceptives, or certain medications may interfere with the menstrual cycle, inquire with your MD or pharmacist if you are taking any meds..
2) Not only prescription drugs, but recreational (street) drugs can affect your cycle.
3) You may be naturally irregular.
4) weight loss, diteting or change in your diet (eg becoming a vegetarian), stress, changes in your personal life, exercise, being too thin (under 100lbs will cause cycles to cease).
5) Medical conditions: like diarrhea and vomitting, anorexia or bulimia, autoimmune diseases. Hormonal imbalance (if you are still growing or just had menarche or other, such as thyroid imbalance), polycystic ovarian syndrome, anemia (low iron)
What you may want to do:
Eat well, plenty of fruits and veggies, lots of water, exercise within reasonable limits. Talk to your doctor to rule out other possibilities. Your doctor will be able to decide if it would be beneficial for you to be on birth control to be "regular". Use some method of contraception unless your trying to become pregnant. Good luck =0)
Hi, I had the same problem. There are a lot of factors like; change of diet, exercising a lot more than normal or very hard, illness, weight loss or gain.
Also, depending on your age, it could be your cycle regulating itself. If you are concerned talk to your doctor, maybe get on birth control to help regulate it.
stress
hormone imbalnce
Polycystic ovarian syndrome
Google
RN
Diet and exercise
if u just did "it" it will be like that for a year.
If you are very athletic, that can cause a girl’s period to be late. There is also a condition that causes a period to be incredibly irregular. Your best bet is to go talk to your doctor. They can put you on BC, which will regulate your period so it happens at the same time every month.
I’m not sure what the user before me means unless she is insinuating that you are pregnant, but having sex should not cause your period to be chronically late.