WHAT ARE HORMONES?
What are they and what do they do?
In short, they are just natural chemicals in your body that help to keep things functioning the way that they should.9
Just as those hormones create changes in the way your body looks on the outside, they also create changes on the inside. While your body is adjusting to all the new hormones, so is your mind. During puberty, you might feel confused or have strong emotions that you've never experienced before. You may feel anxious about how your changing body looks.10
You might feel overly sensitive or become easily upset. Some teens lose their tempers more than usual and get angry at their friends or families.10
How hormones affect the menstrual cycle?
The average cycle is 28 days but, for some women, it is as short as 21 days, for others it is as long as 35 days. Every month there is a complex interaction between the pituitary gland in the brain, the ovaries and the uterus (or womb). When you first start having periods, it can also take a while before your periods develop a regular pattern.11
Day one of your cycle is the first day of your period. This is when your uterus starts shedding the lining it has built up over the last 28 days. After your period is over, the lining of your uterus starts to build up again to become a thick and spongy ‘nest’ in preparation for a possible pregnancy. On day 14 (for most women), one of your ovaries will release an egg, which will make its way through a fallopian tube and will eventually make its way to your uterus (called ovulation). On day 28 (for most women), if you have not become pregnant, the lining of your uterus starts to shed. This is your period. The blood you lose during your period is the lining of your uterus.11
How does pregnancy happen?
Pregnancy happens when a man’s sperm fertilizes a woman’s egg, which can happen even if you’ve not had sexual intercourse (penetration).12
During sex, semen is ejaculated from the man’s penis into the woman’s vagina. A man's semen (the liquid produced when he ejaculates or "comes") contains millions of sperm. One ejaculation can contain more than 300 million sperm.12
A woman's ovaries release one or more eggs (ovulation) 12-16 days before her next period. The man’s sperm enters the woman's body through her vagina, then travels through her cervix and womb to the fallopian tubes, where an egg is fertilized (conception). The egg can be fertilized by sperm contained in semen or pre-ejaculate.12
How do hormones in contraception work?
The hormones in contraceptives don’t only prevent ovulation. Some also prevent fertilized eggs from implanting into the womb. Others cause the mucus in the cervix (the opening of the womb) to become thick and sticky, making it harder for the sperm to move and reach the egg cell.13
Hormonal contraceptives are only reliable if they are used properly. If, for instance, a woman forgets to take her pill one day, her ovaries may release an egg (ovulation) and she could become pregnant.13
The effectiveness of hormonal contraceptives may be reduced by medication such as antibiotics, blood- pressure-lowering or cholesterol-lowering drugs, antifungal drugs or herbal products like St. John’s wort.
Also, if women who take the pill vomit or have diarrhea, the pill may no longer provide enough protection. So, they have to use another form of contraception too – for instance, a condom.13
How will contraception affect my period?
Birth control pills were once only packaged as 21 days of active hormone pills and 7 days gap. During the gap, menstrual period-like bleeding occurs. Today women have many more options — from regimens with 24 days of active pills and four days of hormone free pills to regimens that are all active pills.14
Some extended-cycle pill regimens have active hormone pills every day for three months, followed by a week of placebo or low-dose estrogen pills. You experience menstrual bleeding during that week. Newer extended-cycle regimens involve taking active pills continuously for one year and can stop all menstrual bleeding. Continuous or extended-cycle regimens have several potential benefits. They prevent hormone changes responsible for bleeding, cramping, headaches and other period-related discomforts. It can be convenient to skip a period during important events or trips.14
Studies have shown that the effect of the birth control pill on weight is small — if it exists at all.14