Written by Dr.M.D.Mazumdar, MD
Oral Contraceptive Pills (OCP), or birth control pills as they are more commonly called, are a hormonal method of contraception.
All oral contraceptives discovered so far are applicable only in the female. No pills for males have been discovered, although research is on to find a suitable hormone preparation.
Almost all the OCP's are combinations of the female hormones, estrogen and progesterone. The estrogens commonly used are either mestranol 50 micrograms or ethinyl estradiol, 20 to 50 micrograms.
A variety of progesterones are used in combination with the estrogen. The commonest are levonorgesterol, progestin, norethisterone, norgestrel, drospirenone, ethynodiol diacetate etc.
The OCPs are more effective than other birth control methods like condoms, the rhythm method and the intrauterine contraceptive devices (IUDs).
A newer birth control pill on the market which does not contain either estrogen or progesterone is Centchroman. It is believed to be more effective than the standard OCPs containing estrogen and progesterone.
The birth control pills work mainly by preventing ovulation. In a normal menstrual cycle, the pituitary gland secretes the hormones FSH and LH to stimulate the ovary to release an egg ('ovulation"). The hormones estrogen and progesterone are secreted by the ovary during and after ovulation.
When birth control pills are taken, the levels of estrogen and progesterone is increased in the blood. This sends a negative feedback message to the pituitary gland to stop secreting FSH and LH. The lowered levels of FSH and LH fails to stimulate the ovaries and ovulation is prevented. Lack of ovulation prevents a pregnancy from occurring.
The pills also work by causing changes that make the endometrium unreceptive to a fertilized ovum if ovulation and fertilization do take place in any menstrual cycle.
The progesterone in the pills also makes the cervical mucus hostile to the sperm.
Another type of Multiphasic birth control pills (Estrostep 21) contains the same level of progesterone (1 mg norethindrone acetate) in each pill throughout the pack but varying levels of estrogen at different phases - usually 20mcg for five days, 30mcg for seven days, 35 mcg for nine days followed by seven inactive pills.
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The pills usually come in packs of 21 tablets or 28 tablets. In the 28 day pack, the first 21 pills are the active pills and the last seven, usually of a different color, are inactive and does not contain any hormones.They may however contain vitamins or iron supplements.
If the 21 day pack is taken, the first pill has to be started from the 1st day of menstruation or on the first sunday after the period starts. One pill is to be taken every night daily until the pack is finished. The next period occurs within the next 7 days. The second pack is then started from the 1st day of that period or on the first sunday after the period starts.
If the 28 day pack is taken, the entire pack is taken until the pack is finished. The period will usually occur while on the inactive pills. The second pack is then started from the 1st day of the period or on the first sunday after the period starts.
Packs containing 24 active pills and 3 inactive pills have also come on the market.
According to some researchers, birth control pills should not be taken continuously for more than 2 years to prevent a condition known as 'post pill amenorrhea'. A gap of 6 months should be given after 2 years to restore the normal hormonal balance of the body and for ovulation to recur. Then the second course of OCP's should be started.
The morning after pill, also called the Plan B or emergency contraception, is a method of contraception meant to be used when other contraceptive methods have failed, or when sexual intercourse takes place without any birth control methods being used.
It consists of pills containing a high dose of progesterone (usually 150 micrograms). If the emergency contraceptive course consists of two pills , each pill will contain 75 mcg each. The first pill should be taken immediately after the unprotected sex and the second within 72 hours. If the contraception comes in a single dose, then the pill will contain 150mcg. It has to be taken within 72 hours after sex. This disrupts the endometrium and prevents implantation of a fertilized ovum, if fertilization does occur in that cycle.
If the morning after pill is not available, then birth control pills instead of the Plan B may be used as a substitute. If the birth control pills contain 30 mcg of progesterone, then 5 pills taken together will be equivalent to 1 morning after pill(150mcg). If the birth control pills contain 25 mcg of progesterone then 6 pills taken together will be equivalent to a single morning after pill. The effect of these pills will be the same as the morning after pill.
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