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The monthly fertility pattern which occurs regularly in most women beginning at puberty and ending at menopause is called the menstrual cycle. Each cycle is divided into two parts --- before ovulation and after ovulation. Over a 28-day period the cycle typically follows this pattern:
Part 1. Day 1 of your cycle is the day menstruation (or bleeding) begins and usually lasts from 3-5 days. This first part, from menstruation to ovulation, may vary from 13 to 20 days in length and is referred to as the follicular phase of the cycle, as this is when the follicle develops the mature egg. The actual length may not only differ from one woman to another but also differs in some women from month to month. It is during this critical first part of the cycle that fertilization can occur. The regularity of this pattern may be upset by such common occurrences as sickness, stress, physical exertion or even climate changes. A rise in the level of Luteinizing Hormone (LH) accompanies a change in the cervical mucous in anticipation of the follicle rupturing and releasing a mature egg towards the end of this first half of the cycle. (The change in cervical mucous allows sperm in the vagina access to the uterus and fallopian tubes.) This surge in hormone level can be detected in your urine and is commonly used to predict ovulation and your fertile period. The ruptured follicle becomes the corpus luteum and produces hormones that effect the rest of the cycle.
Part 2. The second part of the cycle, from ovulation to menstruation, is about the same length in all women, and is called the luteal phase. It is during this part that the egg travels down the fallopian tube toward the uterus --- an event which consistently occurs 14 to 16 days before the onset of menstruation regardless of the length of a woman's menstrual cycle. If a single male sperm unites with the egg while it is in the tube the fertilized egg may attach to the spongy lining of the uterus. Pregnancy begins if this "implantation" takes place. If fertilization does not take place the egg will break apart in a day or two. At about Day 25, hormone levels begin to drop. This causes the lining of the uterus to break down and in a few days it is shed in a menstrual period. Another cycle has begun.
For access to some excellent mini movies produced through PBS covering human reproduction, and the role of sperm and egg, go to the following link PBS MOVIES
Pregnancy can be detected by the rise in HCG levels, which will quickly rise after successful implantation of an embryo. Some home tests can detect this rise as soon as within 10-12 days past ovulation. Go to our Fertility Store to view or order LH and HCG test kits.
Miscarriage:
It's a topic that's not often discussed and yet it happens in as many as 25 percent of all pregnancies. Miscarriage is a term that refers to the loss of a pregnancy within the first 20 weeks, and it most often occurs in the first trimester. You may also hear the term spontaneous abortion used to describe miscarriage. There are other categories of miscarriage that include inevitable, missed, and incomplete abortion. In general, first trimester loss occurs for one of two reasons:
- A fetus that is not developing properly and/or
- A placenta that is not attaching to the uterine wall properly There are numerous reasons for a pregnancy to begin and end so soon. It is believed that the vast majority of these early losses are due to genetic or chromosomal problems with the fetus.
Other possible causes are:
- Blighted ovum, a condition that is usually genetic in which the placental sac may be developing without a fetus
- Uterine infection
- Certain medications taken by the mother (although this is a rare cause)
- Low hormone levels, particularly progesterone, which may signify an unhealthy pregnancy at the start
- Structural abnormalities of the uterus
- Fibroid tumors
- Immune system dysfunction
The odds for miscarriage depend to some extent on the age of the woman. The older the woman, the higher the risk for miscarriage. The miscarriage rate is not higher for artificial insemination with donor sperm than it is for anyone else getting pregnant, and is probably actually a little lower because of the strict donor selection process. Many miscarriages happen so early in the pregnancy that they are not even recognized as such, and may be interpreted as just having a late period. The typical first sign of an impending miscarriage is spotting or cramping well after conception. Some women may notice diminished pregnancy symptoms while others may not notice any symptoms at all and are unaware that the pregnancy is nonviable at their first OB visit. Patients having bleeding and cramping want to know if their pregnancy is healthy or not, and the medical profession may not be able to stop the process, but can provide information in a timely manner. Miscarriage is confirmed through ultrasounds and hCG blood tests. The good news is that experiencing one miscarriage usually has little to no predictive value on future successful pregnancies, however you should inform your physician if you have repeated miscarriages. Reproductive endocrinologists are not only expert in facilitating conception, but also in helping women with recurrent pregnancy loss by providing the diagnostic workup and possible treatment options.