The size of your uterus must be reconciled with the gestational age of your baby, or there’s something wrong. Twins, misjudgment of dates, and even non-pregnancy should be suspected if dates don’t equal size. On your initial visit you will be asked a number of questions so as to render or update a careful history, depending on whether you are a new patient or not. Prior records from your last doctor or from consultants (like infertility specialists) who have been caring for you will be sent for. If there's a history of pre-existing conditions-hypertension, irritable bowel disease, diabetes, thyroid, etc., this will mean you're out of the "normal" pregnancy group. If the doctor herself doesn’t obtain your history, you will probably be questioned by her regarding any unusual things that came out of the inquiries so far.
The Initial Exam
In addition to routine blood work and vaginal cultures, the initial physical exam will be used to assess both your general maternal health and the size of your uterus. If it's too early to hear your baby's heartbeat, then your doctor will use the size of your uterus to give some indication as to whether there is someone growing inside of it to make it the size expected for the gestational age. For instance, if you’re six weeks pregnant, but your uterus is 12 weeks by size on the exam, either the estimate of gestational age is wrong, or you’ve got twins or fibroids. On the other hand, if you’re 12 weeks along, but the size of your uterus by exam is less than six weeks, either you had a delay of your ovulation (making dating of your pregnancy from your last menstrual period inaccurate); there’s a problem with your baby’s growth, which would constitute a miscarriage concern; or you’re not pregnant at all.
Pelvimetry - Measuring Your Pelvis
There are manual measurements of your pelvis at the initial exam. By manual, I really do mean by hand, because in the course of your vaginal examination your doctor will size up your pelvic measurements by comparing them with her own hand measurements. Over the years, your doctor has come to know a personal “yardstick”—her own hand, and by seeing how her examining fingers lay down against the length and width of your pelvis she can determine the likelihood of a successful passage of your baby through your pelvis. When such an exam is done with X-rays (rare in today’s modern obstetrics), it's called pelvimetry. When it’s done by your doctor’s hand, it’s called skill.