SECTION 3: Symptoms & Tests
How pregnancy occurs:
Pregnancy occurs when a sperm produced by a male, fuses with an ovum produced by a female.
Signs and symptoms:
During pregnancy a woman's body undergoes a number of changes to allow the fetus to develop inside the womb. The symptoms of pregnancy vary from woman to woman.

Stages of Pregnancy
Pregnancy stages - There are three stages of pregnancy called trimesters. Each trimester is three months. The word "trimester" comes from a Latin word meaning "three months long."
First trimester of pregnancy – The first trimester of pregnancy is the early stage of pregnancy from conception to 12 weeks gestation, or about 14 weeks from the first day of the last normal menstrual period (LNMP).
Second trimester of pregnancy - In the second trimester the embryo, now known as a fetus, is recognisable as human in form, but is not developed enough to be viable if born. The second trimester is often called the planning trimester and it is from 13 weeks after the last menstrual period (LMP) to 26 weeks of pregnancy.
Third trimester of pregnancy - The third trimester of pregnancy lasts from 28 weeks after the last menstrual period (LMP) until the birth, which usually occurs between the 38th and 42nd week of pregnancy.

Calculating Pregnancy Due Date
It is difficult to precisely conclude the date of conception in order to confirm date of confinement. Calculating pregnancy due date is usually computed from the first day of the last regular period.
a) Nagele’s rule In the calendar, this can be figured by taking that date, subtracting three months, and adding seven days and add one year This method is more accurate when the cycle is of 28 days adjusted with short and long cycle.
b) Fundal height using finger breadths: Measured on the anterior wall of abdomen, with finger breadths. It provides a good estimation of duration of pregnancy and helps in identifying IUGR, multiple gestation etc. Factors Affecting Accuracy: Obesity , amount of liquor, multiple gestation ,fetal size and attitude and width of examiner’s finger.