Question

consider how birth control pills, intrauterine device and condoms prevent pregnancy.

please type

Answer 1

CHEMICAL METHODS
Chemical substances, which destroy the sperms, are applied in female genital tract before coitus. Destruction of sperms is called spermicidal action. The spermicidal substances are available in the form of foam tablet, jelly, cream and paste.
ORAL CONTRACEPTIVES (PILL METHOD)
Oral contraceptives are the drugs taken by mouth (pills) to prevent pregnancy. These pills prevent pregnancy by inhibiting maturation of follicles and ovulation. This leads to alteration of normal menstrual cycle. The menstrual cycle becomes the anovulatory cycle.
This method of fertility control is called pill method and pills are called contraceptive pills or birth control pills. These pills contain synthetic estrogen and progesterone.
Contraceptive pills are of three types: 1. Classical or combined pills
2. Sequential pills
3. Minipills or micropills.
1. CLASSICAL OR COMBINED PILLS
Classical or combined pills contain a moderate dose of synthetic estrogen like ethinyl estradiol or mestranol and a mild dose of synthetic progesterone like nor- ethindrone or norgestrol.
Pills are taken daily from 5th to 25th day of menstrual cycle. The withdrawal of the pills after 25th day causes menstrual bleeding. The intake of pills is resumed again after 5th day of the next cycle.
Mechanism of Action
During the continuous intake of the pills, there is relatively large amount of estrogen and progesterone in the blood.
It suppresses the release of gonadotropins, FSH and LH from pituitary by means of feedback mechanism. Lack of FSH and LH prevents the maturation of follicle, and ovulation. In addition, progesterone increases the thickness of mucosa in cervix, which is not favorable for transport of sperm. When the pills are withdrawn after 21 days the menstrual flow starts.
2. SEQUENTIAL PILLS
Sequential pills contain a high dose of estrogen along with moderate dose of progesterone. These pills also prevent ovulation.
Sequential pills are taken in two courses:
i. Daily for 15 days from 5th to 20th day of the
menstrual cycle and then
ii. During the last 5 days, i.e. 23rd to 28th day.
3. MINIPILLS OR MICROPILLS
Minipills contain a low dose of only progesterone and are taken throughout the menstrual cycle. It prevents pregnancy without affecting ovulation. The progesterone increases the thickness of cervical mucosa, so that the transport of sperms is inhibited. It also prevents implantation of ovum.
DISADVANTAGES AND ADVERSE EFFECTS OF ORAL CONTRACEPTIVES
About 40% of women who use contraceptive pills may have minor transient side effects. However, long term use of oral contraceptives causes some serious side effects. Some of the side effects are rare, but may be dangerous.
Following are the disadvantages and adverse effects of oral contraceptives:
1. Major practical difficulty is the regular intake of the pills
2. May not be suitable for women having disorders such as diabetes, cardiovascular diseases or liver diseases
3. Clotting tendency of blood due to suppressed production of anticoagulants in liver
4. Hypertension and heart attack
5. Increases the risk of stroke
6. Tenderness of breast and risk of breast cancer
(but may decrease the risk of ovarian and uterine cancer).
LONG-TERM CONTRACEPTIVES
To avoid taking pills daily, the long-term contraceptives are used. These contraceptives are in the form of implants containing mainly progesterone. The implants which are inserted beneath the skin release the drug slowly and prevent fertility for 4 to 5 years. Though it seems to be effective, it may produce amenorrhea.

INTRAUTERINE CONTRACEPTIVE DEVICE (IUCD) – PREVENTION OF FERTILIZATION AND IMPLANTATION OF OVUM
Fertilization and the implantation of ovum are prevented by inserting some object made from metal or plastic into uterine cavity. Such object is called intrauterine contraceptive device (IUCD).
MECHANISM OF ACTION OF IUCD
Intrauterine contraceptive device prevents fertilization and implantation of the ovum. The IUCD with copper content has spermicidal action also. The IUCD which is loaded with synthetic progesterone slowly releases progesterone. Progesterone causes thickening of cer- vical mucus and prevents entry of sperm into uterus.
The common IUCDs are Lippes loop, which is ‘S’ shaped and made of plastic and copper T, which is made up of copper. It is inserted into the uterine cavity by using some special applicator.
DISADVANTAGES OF IUCD
IUCD has some disadvantages. It has the tendency to: 1. Cause heavy bleeding in some women
2. Promote infection
3. Come out of uterus accidentally.
MEDICAL TERMINATION
OF PREGNANCY (MTP) – ABORTION
Abortion is done during first few months of pregnancy. This method is called medical termination of pregnancy (MTP). There are three ways of doing MTP .
DILATATION AND CURETTAGE (D AND C)
In this method, the cervix is dilated and the implanted
ovum or zygote is removed.
VACUUM ASPIRATION
The implanted ovum is removed by vacuum aspiration
method. This is done up to 12 weeks of pregnancy.
ADMINISTRATION OF PROSTAGLANDIN
Administration of prostaglandin like PGE2 and PGF2 intravaginally increases uterine contractions resulting in abortion.