Natural birth control is method in which couple abstain from sex or avoids pregnancy without using any contraceptive method. In natural birth control methods either the sperms are not allowed to enter female reproductive system or sex is avoided in fertile days of menstrual cycle.
This is good birth control method for females having regular menses but not 100% effective as ovulation depends on many factors such as stress, illness and length of menstrual cycle which may vary month to month. Still this method is 90 % effective when used by woman understanding her fertility signs and cooperation by her partner.
Safe period method or Calendar based method
This involves avoiding sexual intercourse on most fertile days in a menstrual cycle. In a menstrual cycle the chances of conceiving is highest near ovulation. Ovulation is process of release of mature egg from ovary and this egg remain available for fertilisation by sperm for next 24 hours. After which it disintegrates and conception does not occur. So avoiding sex during ovulation results in birth control. Days past ovulation are considered to be safe period.
Understanding fertility days
These fertile days can be 9 days long 5 days before ovulation and 3 days after ovulation. Ovulation can be determined by a female body hormonal changes as cramps in lower abdominal, soar breasts, higher urge for sex. You can record your body temperature daily in afternoon and prepare a chart. Your body temperature will be higher (0.4 F~0.8 F) on first day of ovulation.
Withdrawal method
As the name suggests this method involves withdrawing penis from vagina right before orgasm and ejaculating outside and thus preventing sperms to enter inside female reproductive system.
This method is 95% effective but involves proper control by male partner as well as timing is important. If timing gets wrong then pregnancy may occur.
You should consult your doctor to determine your ovulation as she can help you in determination of your fertile days.