physiology of pregnancy, placental hormons and pregnanc diagnosis tests
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Answers
Pregnancy is the time from fertilization of an egg, also known as conception, to birth. Getting pregnant and growing a human from scratch is a very complicated biological process that takes a lot of resources. As a result, pregnancy can have a wide range of effects on the mother, both physically and emotionally.
Each egg that is released during a menstrual cycle travels to your uterus. However, unlike unfertilized eggs that proceed unaltered and then disintegrate when they get there, a fertilized egg develops into a tiny human embryo on the way. On reaching the uterus, the embryo implants itself in the uterine wall, develops into a fetus, and steadily grows, until about nine months later it is ready to emerge into the outside world as a newborn baby.
Signs and symptoms
If you are fertile, sexually active, and become pregnant, the first thing you are likely to notice is a late or missing menstrual period. Fertilization of an egg triggers changes in the production of various hormones almost immediately, and hormone changes evolve and persist throughout your pregnancy to help you grow a healthy baby. Unfortunately, these changes may also cause unpleasant side effects. As a result, in addition to a missed period, many women experience tender, swollen breasts, fatigue, nausea and vomiting, or morning sickness during the first few weeks of becoming pregnant.
Diagnosis
If you are experiencing some or all of the early signs and symptoms of pregnancy, or if you suspect you might be pregnant, you may want to take a home pregnancy test. These tests are designed to detect the presence of human chorionic gonadotropin in a sample of your urine. This hormone becomes detectable in urine once the embryo has implanted in the uterus, typically about 8 or 9 days after fertilization.
Whether your home pregnancy test is positive or not, a visit to your healthcare provider can confirm if you are pregnant. Much like the home pregnancy test, this is usually done by testing a urine sample or blood sample for human chorionic gonadotropin (HCG). Your healthcare provider may also perform a physical exam of your uterus and cervix, looking for other physical signs that you are pregnant. For example there may be signs that your uterus has enlarged, that your cervix is larger and softer, or that your cervix is blueish in colour. Less commonly, and usually only if you are experiencing vaginal bleeding or abdominal pain, your healthcare provider may recommend a transvaginal ultrasound to confirm whether you are pregnant. The earliest observable pregnancy-related change that can be seen with ultrasound is the development of a gestational sac. Later, ultrasound images are commonly used to monitor fetal development over the course of pregnancy.
Once you know for sure that you are pregnant, you can calculate an approximate delivery date for when your baby will be born; usually accurate to within a couple of weeks. As the exact day your egg was fertilized is difficult to pinpoint, the beginning of your pregnancy is usually taken to be the first day of your last normal menstrual period.
Physiological changes that occur during pregnancy
Hormonal: The menstrual cycle refers to the normal changes in your ovaries and uterus that make an egg accessible for fertilization and prepare your uterus for pregnancy. It typically occurs once every 28 days. If you are ovulating normally, an egg, or ovum emerges from one or other of your ovaries, leaving behind a structure called the corpus luteum. This structure produces large amounts of progesterone and estrogen, hormones that help prepare your uterus for implantation of a fertilized egg. If the egg is not fertilized, the corpus luteum degenerates, causing progesterone and estrogen levels to drop, and menstruation to begin. If the ovum is fertilized, on the other hand, the corpus luteum remains intact and continues to maintain the hormone levels you need to keep your uterus baby-friendly. Eventually, the placenta develops the ability to secrete the necessary hormones itself, and the corpus luteum typically disappears after 3 to 4 months.
In addition to progesterone and estrogen, human chorionic gonadotropin also spikes in early pregnancy. The levels of this hormone double every two days in the first 10 weeks of pregnancy. Its primary role is to prevent any further menstruation, and to prepare the placenta - the organ that connects the fetus to the uterus. The placenta allows the fetus to be supplied with nutrients and oxygen, as well as providing a route for the removal of toxic waste products
Although many signs and symptoms of pregnancy are related to hormonal changes, there are also many that occur due to the growing fetus invading the spaces that were previously occupied by your other organs.