1. Physiological bases of contraception Lecture -6
Dr. Zahoor
Dr. Shaikh Mujeeb Ahmed

2. Contraception
Is prevention of pregnancy before the implantation has taken place .

3. Methods of Contraception
Blockage of sperm transport to ovum
Natural Methods
Rhythmic abstinence
Coitus interruptus
Barrier methods
Use of spermicidal
Sterilization
tubal ligation
vasectomy

4. Methods of Contraception (cont…)
Prevention of ovulation
Hormonal contraceptive (OCP)
Blockage of implantation
IUCD
Emergency contraception/morning after pill

5. 1. Blockage of sperm transport to ovum
Natural methods
Rhythmic abstinence
Coitus 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

6. Basal 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
Coitus interruptus: withdrawal before ejaculation

7. Barrier methods Barrier methods: prevents entry of
sperm into vagina or uterus
For males (condom)
For females ( diaphragm or cervical cap )
Sponge
Placing Spermicidal Agents :
Kill the sperms or decrease their motility
Suppositories
Gel
Foam tablets
Creams

8. Sterilization Permanent Methods
Female sterilization ( i.e tubal ligation or Tubectomy)
Male sterilization (vasectomy):

9. 2. Prevention of ovulation Hormonal contraceptive
Oral contraceptives
Combined pills
Estrogen alone
Synthetic Progesterone alone
Injectable .

10. 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

11. 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

12. Hormonal contraceptive(continued)
Injectable long acting prgestational preparation which can be given once in a three months
Sub cutaneous implants of progesterone have also been tried ,(can prevent pregnancy up to 5 years)
Dermal patch

13. 3. Blockage of implantation
Intra Uterine Contraceptive Device(IUCD):
Are devices which are introduced & left inside the uterus for longer period of time .
Mechanism of action :
They produce local nonspecific inflammatory reaction in the endometrium & disturbing the endometrial cyclic changes & prevent implantation of blastocyst .

14. Intra Uterine Contraceptive Device(IUCD):

15. Intra Uterine Contraceptive Device(IUCD)(continued)
Side effects :
Bleeding
Abdominal pain / backache
Displacement
Perforation

16. Average failure rates of common contraceptive techniques
Contraceptive method
Average failure rate (100 women-year)
Natural method
20-30
Chemical contraceptive 20
Barier method
10-15
OCP
2-2.5
IUCD 4

17. THANK YOU