Conception and Pregnancy
Conception is defined as the union of a single egg and sperm. Conception also signifies the beginning of a pregnancy.
Conception is not an isolated event but part of a sequential process involving ovulation (release of egg from ovary) gamete formation, fertilization (union of sperm and egg) and implantation into the uterine wall.
Pregnancy lasts (give or take) ten lunar months, nine calendar months, forty weeks, or 280 days.
What Are The Symptoms of Pregnancy?
Symptoms of pregnancy can vary according to each woman's biology and can mimic the symptoms of many other conditions.
Common symptoms can include:
- Missed menstrual period
- Nausea or vomiting
- Tender or sore breasts
- Spotting (known as implantation bleeding), possibly accompanied by cramping
- Hormone-induced headaches
- More frequent need to urinate
- Cravings or aversions to certain foods
- Thickening and/or whitening of vaginal fluids
- Mood swings
If you suspect you may be pregnant, it is important to get tested as soon as possible so that you can identify your options and set up prenatal care.
The most common method of testing for pregnancy is through a Home Pregnancy Test (HPT), which measures the amount of a pregnancy hormone called hCG in a woman's urine. These tests can be purchased at most drugstores and supermarkets, can be administered at clinics and doctors' offices, and are a quick and easy method of pregnancy testing. HPTs are highly accurate when used one week after a missed period. False positive results are rare, as a positive will only show up if there is hCG in the urine. It is possible for a false negative if testing is performed too early and hCG levels are too low for detection.
A physician can also administer a blood test which checks hCG levels in the blood (and can detect lower levels than a HPT).
Biology and Duration:
Length of pregnancy is calculated by the first day of a woman's last menstrual period until the day she gives birth. However, conception occurs about two weeks after the first day of her last menstrual period, so the post-conception age of the fetus is two weeks less, for a total of 266 days.
Intrauterine development is divided into three stages: ovum, embryo (embryonic) and fetus (fetal).
The Ovum Stage lasts from conception to day fourteen and involves cellular replication, blastocyst formation, establishment of the germ layers, and initial development of the embryonic membranes.
Stage of the Embryo: lasts from day fifteen until about eight weeks after conception, or until the embryo measures 3mm. This is the most critical time for organ and main external system development. The rapidly dividing cells are particularly vulnerable to malformation caused by teratogens.
Teratogens are substances or exposure to substances (i.e. cigarettes, drugs and/or medications, alcohol) that cause abnormal development.
The Fetal Stage lasts from nine weeks until the pregnancy ends. Changes in this period - although long - aren't nearly as dramatic as they are in the other stages as the structures and functions are already in place.
The fetus is less vulnerable to teratogens, with the exception of those that affect the central nervous system.
Viability describes the ability of the fetus to survive outside of the womb. While the golden standard for viability was once twenty-eight weeks, viability can be seen as early as twenty-two weeks. Limitations on survival include central nervous system function and the capacity of lungs to properly oxygenate the fetus outside the uterus.
Seeing a health care provider regularly throughout pregnancy is important to ensure that the pregnancy is progressing without complications and to identify early on whether the pregnancy may be high risk and requires special care. Health care providers will may perform the following during routine checks:
- Due date calculation
- Blood test, including infection tests, blood type test, Rh factor test, and iron level check
- Blood pressure check
- Weight monitoring
- Fetal growth and heart checks
- Urine tests to identify preeclampsia, diabetes, or urinary tract infections
- Blood glucose challenge, with possible additional glucose tolerance test
- Prenatal screenings for fetal health problems
- Chorionic Villus Sampling (CVS)
- First trimester screen
- Maternal serum screen, aka Quad Screen or AFP
- Group Beta Strep Testing
Many health care providers will also provide educational materials and local resource information in addition to health care.
Additional Pregnancy Resources:
The toll-free line 1-800-311-BABY (1-800-311-2229) offers assistance in finding low cost or free prenatal care to any woman in the United States. Spanish speakers can call 1-800-504-7081.
American Pregnancy Association is a national non-profit health organization committed to promoting reproductive and pregnancy wellness through education, research, advocacy, and community awareness. It also a link describing insurance options for pregnant women.
March of Dimes - Excellent source of information that is devoted to helping moms have full-term pregnancies and research the problems that threaten the health of babies.
Pregnancy Options - a workbook to aid in making decisions regarding a pregnancy.
Planned Parenthood - Planned Parenthood provides a wide range of services and can assist with prenatal care.
WomensHealth.gov - This is a site run by the U.S. Department of Health and Human Services. There is a wealth of information to assist pregnant women.
Epigee Women's Health offers real photos of the developing fetus in the womb according to trimester.