A woman is said to be pregnant when the sperm fertilizes the ovum, and the tiny fetus attaches itself to the uterus. When this occurs, the brain sends signals to the ovaries to stop the production of ovum, and the focus is on the production of hormones which are important for the healthy development of the fetus. As ovulation does not take place during this time, there are no chances of having menstrual periods during the nine months of pregnancy. However, there are cases where women have reported to have experienced menstruation while they were pregnant. In such situations, the question that women ask is: can menstruation occur during pregnancy? The answer to this question is an absolute 'NO'. However, this does happen, and hence, it is important to unravel the mystery surrounding the phenomenon of menstrual bleeding during your nine months gestation period. Is it Possible to Have Periods During Pregnancy? As it is quite clear that menstruation cannot possibly occur during pregnancy, the vaginal bleeding that one observes during this time can be due to a variety of reasons. In some cases, it may just be light spotting, while for some, it may be similar to their menstrual bleeding. The reasons for bleeding during pregnancy can be different, and though in several cases it is not a matter of worry, there have been cases when bleeding during pregnancy is an indicator of something very serious. Reasons for Vaginal Bleeding During Pregnancy Menstrual Period Although it is not possible to have menstrual period during pregnancy, some women do experience regular menstruation, especially in the first month of gestation. This happens when the conception occurs very close to the date of their actual period. Though this is quite normal, it can cause problems while determining the gestation period because normally, the due date is usually calculated from the first day of the last period. In such cases, the help of an electronic pregnancy scan has to be taken to determine the delivery date. Implantation Bleeding or Spotting Spotting or light bleeding is said to occur when implantation occurs. Implantation is the process when the fertilized egg, i.e. the fetus, attaches itself to the uterine wall. This happens five to ten days after conception; however, implantation bleeding lasts only for a very short time, i.e. for not more than 3-4 days. Hormonal Changes Another reason that can cause bleeding is changes in the hormonal level of the body. This also occurs during the early stage of pregnancy and is said to be a common occurrence. As pregnancy leads to several hormonal changes in the body, one may experience vaginal bleeding, which is often mistaken as menstrual bleeding. Ectopic Pregnancy Ectopic pregnancy is one of the most serious causes of the occurrence of vaginal bleeding during pregnancy. It is a condition that occurs when the fetus attaches itself to a place other than the uterus lining, especially the fallopian tubes. As there is no space for the fetus to grow in the fallopian tubes, the chances of organ damage and even death are very high in such conditions. Usually, when ectopic pregnancy has occurred, one will experience stomach cramping along with vaginal bleeding. Miscarriage Bleeding during pregnancy, especially during the first three months, can be an indicator of miscarriage. This is quite a common phenomenon as it is said that most of the pregnancies get naturally terminated even before the woman knows that she is actually pregnant. Just as in the case of ectopic pregnancy, even miscarriage can cause abdominal pain apart from bleeding. Problems in the Placenta The placenta is the vascular structure that is found on the upper part of the uterus which performs the function of providing nutrition and oxygen to the fetus. It is also responsible for eliminating the baby's waste. When some problem occurs to the placenta, bleeding is likely to occur. There are mainly two problems of the placenta that can cause bleeding during pregnancy. One is called the placenta previa, which is a condition where the placenta gets attached to the lower part of the uterine wall, thus covering the cervix. The other problem is placenta abruption, which is caused when the placenta gets separated from the wall of the uterus. Both these conditions are dangerous and need immediate medical attention. Bleeding occurring during pregnancy is not menstruation per se, but it may be caused due to some other reasons. As the causes of vaginal bleeding during gestation period can be serious, it is important that you consult your gynecologist to ensure a healthy and safe pregnancy. Disclaimer: This Buzzle article is for informative purposes only, and should not be used as a replacement for expert medical advice.