10. Gestational age:
| a. | the expected date of delivery can be calculated using Naegele's formula | |
| b. | is accurately assessed by vaginal examination between 10 and 12 weeks | |
| c. | is accurately assessed by abdominal examination between 14 and 18 weeks | |
| d. | can be assessed by measurement of sac size between 6 and 8 weeks | |
| e. | can be assessed by measurement of crown rump length in the second trimester |