Gestational age

Gestational age (GA) is the duration of pregnancy estimated from first day of last normal menstrual period to the current day.

The following methods are used in estimation of gestational age:

Last normal menstrual period

Naegele’s rule is used to estimate gestational age from LNMP in which seven days are added to the first day of your LMP and then three is deducted from the current  month.

Fundal height measurement

A distance between pubic bone and the uterine fundus. The results correspond to spefic gestational age.

Obstetric USS

Obstetric USS uses the size of crown-rump length (CRL) in 1^st trimester, Biparietal Diameter (BPD),Head Circumference (HC),Femur Length (FL) and Abdominal Circumference (AC) in 2^nd trimester, .femoral epiphyseal ossification centers, Proximal tibial ossification centers  and the proximal humeral ossification centers in 3^rd trimester.