What are the first signs of pregnancy?

For most women, the first sign of pregnancy is when their periods stop. Although the absence of menstruation can be caused by many things if, in addition, a woman's breasts feel swollen or tender and she feels nauseous - especially in the morning - it is likely that she is pregnant. A pregnancy test can confirm this.

Possible Causes of a Missed Period

  • Pregnancy is the most common cause of a missed period.
  • Birth control pills - some women who use this form of contraception may not have periods. When you stop taking birth control pills, it can also lead to three to six months of missed or abnormal periods.
  • Breastfeeding can cause missed periods, but you may still get pregnant without periods when you are breastfeeding. See Lactational Amenorrhea
  • Certain medications can cause changes in your menstrual cycle. Check with your health provider about changes if you are taking a new medication.
  • Some illnesses can postpone your period; it will usually resume its normal cycle when you are healthy.
  • Malnutrition and low body weight (possible results of poor eating habits) can cause disruptions in your cycle.
  • Excessive exercise can disrupt the production of hormones in your body and stop menstruation.
  • As menopause approaches, periods become irregular and eventually stop.

See your doctor to evaluate changes in your menstrual cycle.

How can you calculate how long you have been pregnant?

Conception takes place around the time of ovulation when the egg is released from the ovary. Ovulation takes place midway through the menstrual cycle, on about the 14th day if the first day of menstruation is taken as day one.

The beginning of a pregnancy is calculated from the first day of the last period; a term pregnancy will last approximately 40 weeks.

What if you have just come off "the pill"?

If a woman gets pregnant within a couple of months of coming off the contraceptive pill she may have experienced irregular ovulation and irregular periods or even none at all.

Under such circumstances it is difficult to reliably estimate how long you have been pregnant, and an ultrasound examination is more useful.

An ultrasound scan performed in the first half of pregnancy will give the most reliable and accurate estimate by working out the size of the fetus. Every maternity hospital will provide this as a routine service to pregnant women.

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