Lecture by Dr.Mohammed Sharique Ahmed Quadri

Assistant professor ,PhysiologyAl Maarefa College

Contraception

Is prevention of pregnancy before the implantation has taken place .

Methods of Contraception Blockage of sperm

transport to ovum1. Natural Methods

1. Rhythmic abstinence 2. Coitus interruptus

2. Barrier methods3. Use of spermicidal 4. Sterilization

a) tubal ligation b) vasectomy

Prevention of ovulation

1.Hormonal contraceptive (OCP)

Blockage of implantation

1.IUCD2.Emergency

contraception/morning after pill

Natural Methods of ContraceptionNatural methods

Rhythmic abstinenceCoitus interruptus

periodic or rhythmic abstinence i.e. avoidance of sexual intercourse during woman’s fertile period Following methods are used

Calendar method:The women predicts when ovulation to occur based

on keeping careful records of previous cycles First fertile period is shortest cycle minus 18 & last

fertile period is longest cycle minus 10

Natural Methods of ContraceptionBasal body temperature method:

Body temperature rises slightly a day after the ovulation

safe period is considered to begin after the basal body temperature remains elevated for 3 days

Cervical mucus method : ovulation time is determined by noting the consistency of the cervical mucus

Coitus interruptus: withdrawal before ejaculation

Barrier methods: prevents entry of sperm into vagina or uterus

For males (condom)For females ( diaphragm or cervical cap )

Spermicidal: SuppositoriesGelFoam tabletscreams

Permanent Methods Female sterilization

( i.e tubal ligation or Tubectomy)

Male sterilization (vasectomy):

Prevention of ovulation Hormonal contraceptive

Oral contraceptives Combined pillsProgesterone only pillOnce a month pill

Injectable

Hormonal contraceptive(continued)

Oral contraceptives Contains synthetic estrogen and progesterone like

steroids (ethinyl estradiol & norgesterel/norethesterone)

Tablets are taken once daily for 21 days commencing at 5th day of menstrual cycle ,it is than stopped for 7 days during which time bleeding occurs

Mechanism of action: They act by inhibiting the release of FSH & LH by

anterior pituitary by negative feedback mechanism, preventing the development of graffian follicle ,ovulation & formation of corpus luteum is prevented

Increases viscosity of cervical mucus ,preventing the sperm penetration

Endometrial maturation is also altered preventing blastocyst implantation

Hormonal contraceptive(continued)

Injectable long acting prgestational preparation which can be given once in a three monthsSub dermal implants of progesterone have also

been tried Dermal patch , vaginal rings

Blockage of implantation Intra Uterine

Contraceptive Device(IUCD):Are devices which are

introduced & left inside the vagina for longer period of time .

They are of two types Unmedicated devices as Lippe’s

loop Medicated devices as copper –T

They are usually changed after three years

Intra Uterine Contraceptive Device(IUCD)(continued)Mechanism of action :

They produce local nonspecific inflammatory reaction in the endometrium & prevent implantation of blastocyst .

Copper increases cellular response & may alter the composition of cervical mucus

It is also believed that IUD increases the motility of fallopian tube ,so ovum reaches the uterus either before it is fertilized, or if fertilized before endmetrium is ready for implantation.

Recently hormone releasing IUCD’s have been devised .for e.g. progetasert releases progesterone which act locally on the endometrium & cervical mucus .

Intra Uterine Contraceptive Device(IUCD)(continued)

Side effects :Bleeding Abdominal pain / backache Displacement Perforation

Blockage of implantation (continued)

Post coital /morning after pill• it is used as emergency contraceptive

measure after unprotected sexual intercourse( most effective within 72 hours )

• It acts by preventing ovulation or cause premature degeneration of corpus luteum, thus preventing the implantation.

• The WHO-recommended regimen for emergency contraception is: 1.5 mg of levonorgestrel as a single dose.

Future possibilities Immunocontraception : in the testing stage is

the vaccine that can induce formation of antibodies against human chorionic gonadotrophin

Male birth control pill: some scientist are seeking ways to manipulate the hormones to block the spermatogenesis

One interesting avenue is being explored to use the Ca blocking drugs ,as Ca is responsible for sperm motility

Average failure rates of common contraceptive techniques

Contraceptive method Average failure rate (100 women-year)

Natural method 20-30Chemical contraceptive 20

Barier method 10-15OCP 2-2.5IUCD 4

References

Human physiology by Lauralee Sherwood, seventh edition

Current Obstetrics & Gynecology diagnosis & treatment

17