I am 17, and I still have not had my period. I do have secondary developments, such as breasts (34C), the necessary hair, etc. I am not a virgin. My question is this: Can I still get pregnant even though I have not had my period?

K.

Women who do not have a period by the time they are 16 are said to have primary amenorrhea. (By contrast, secondary amenorrhea means that menstruation started but periods are no longer occurring regularly.) In order to determine the cause of this condition I would need to search for clues.

The first thing I look for in a young woman with primary amenorrhea is pubic hair growth. Pubertal hair growth starts in response to male hormones from the adrenal gland and continues as the ovaries develop and also contribute male hormones. One common abnormality occurs when the body lacks the ability to respond to male hormones. In this condition, called androgen insensitivity syndrome, the person develops with the appearance of a female despite having a male chromosomal pattern and gonadal production of male hormones. However, the person does not have a uterus or periods, pubic and axillary hair are scant, and testosterone levels are in the male hormone range. In your case, the presence of pubic hair would rule out this possibility, as it tells us that your body is capable of responding to male hormones.

Let's look at other clues. Turner syndrome, a common genetic condition in which where one of the X chromosomes is missing, is usually associated with absent menses and failure to develop ovaries. Without ovaries, you will develop as a female but never undergo puberty. You mention that you have experienced breast development. This means that at the time of puberty your ovaries were producing estrogen, which would presumably rule out Turner syndrome. However, a rare few of women with this abnormality do undergo puberty and then experience permanent cessation of menses. Also, other forms of genetic anomalies may be associated with tumor formation and hormone production. That means a bit more evaluation is necessary to check for such chromosomal problems. Your doctor's first step would be to test your blood for the hormone FSH. If this is elevated, a chromosomal evaluation is in order. If it is in the normal range, we need to look elsewhere for the culprit.

Low body weight, stress, intense exercise (such as experienced by gymnasts or ballet dancers) or obesity associated with polycystic ovarian syndrome may be involved in primary amenorrhea. Another culprit to consider is a congenital (present at birth) malformation of the uterus and/or vagina. Vaginal agenesis (failure to develop a vagina) would obviously result in absent menses. In most of these cases, the uterus also fails to develop. However, in some women, the uterus develops but the vagina does not, or there is a septum blocking release of the menstrual blood. This latter condition is usually readily evident, as these women typically report pelvic pain at regular intervals similar to the expected pattern of menstrual periods.

A careful physical examination, transvaginal ultrasound and FSH blood test can help your physician narrow the possibilities. Until you get a diagnosis, I cannot guess your risk for pregnancy. If your menses are merely delayed, ovulation can begin at any time, and unwanted pregnancy might result. I would not rely on the absence of menses as a form of contraception unless your doctor tells you that pregnancy is impossible.