A squirming parasite infests the human body, bloodily tearing the flesh of the host after nearly a year of infestation, sometimes resulting in death. The plot of the newest sci-fi blockbuster hit of the summer? Nope, it’s pregnancy! This semester has been an especially fertile one, not only because all of the blooming roots of knowledge sprouting forth from our blossoming minds, but also because I have a lot of pregnant (or formerly pregnant) professors. At the start of this semester, I had classes or labs with four expectant mothers. Now, one of the children has been born (s/o to Baby Rowan!) and three more are still ripening. Let’s talk about what’s going on under that bulgy belly. For now, I will just focus on the first trimester because apparently there’s a virtually infinite amount of material you could write on being pregnant.
The earliest pregnancy tests claim to offer accurate results five days before the start of your missed period. In reality, testing this early has only a 60 percent accuracy rate, with tests only reaching 99 percent accuracy a day before your period should have started. Whichever results you’re hoping for—positive or negative—it’s best to be patient when it comes to pregnancy tests to avoid false hope or despair. Most professionals recommend waiting until the day after the expected start of your period to take a pregnancy test in order to decrease the possibility of false results. Pregnancy tests work by detecting Human Chorionic Gonadotrophin (hCG) which is produced by placental cells after the fertilized egg attaches to the uterine wall. For detailed information on the hormonal changes and process of fertilization and zygote implantation, check out my previous columns. Up to half of all fertilized eggs do not end in pregnancy, but instead experience problems with implantation or early development, and are expelled without anyone ever knowing they were “pregnant.” The person’s period will come and go as normal, with no evidence that an egg was ever fertilized. But for now, we’ll just jump right in after a person finds out they’re pregnant, which tends to be about two weeks after actual time of conception.
The start of pregnancy is counted as the last day of a person’s menstrual cycle before conception, which means by the time you find out you’re expecting, you’re already considered to be about a month along. Common bodily responses to the first trimester (lasting through the 13th week of pregnancy) include: morning sickness, enhanced sense of smell and taste, fatigue, frequent urination, gastrointestinal issues, tender breasts, elevated pulse rate and heightened emotions. Most of these issues are caused by the huge spike in hormones, especially hCG, estrogen and progesterone. hCG is the likely culprit for nausea and morning sickness, which tends to affect first-time pregnant people most severely, with symptoms at their worst between weeks seven through 12. People carrying multiple fetuses tend to have worse morning sickness, as well as those with a genetic predisposition to the illness. Severe morning sickness can cross into a rare illness called Hyperemesis Gravidarum (which the most culturally refined of you will recognize as the “Kate Middleton disease”); this involves severe and constant nausea, copious vomiting and an inability to keep down solid foods, even liquids. Sufferers are usually admitted to the hospital for emergency care to avoid dehydration and any other serious effects.
During the first trimester of pregnancy, the fetus grows in size from an orange seed at week five, to a peach at week 13. The embryonic period of fetal development begins at week five, when the blastocyst (group of quickly dividing cells) grows to have three layers and the first precursors of organs. The ectoderm, mesoderm and endoderm will develop into, respectively, the skin and nervous system, circulatory and skeletal system and organs with mucus membranes. In quick succession, nostrils become visible at week seven, eyes appear at week eight, toes at nine, neck at 10, genitals at 11 and fingernails at 12 (insert Juno reference here). The fetus can put its thumb in its mouth at week 13, though they won’t have much of what we would consider sentience (including the ability to feel pain, pro-lifers!) until at least week 24. Other important developmental milestones of the first trimester: the heartbeat becomes audible/visible (on ultrasound) around week 10, and limbs start wiggling in week eight. Taste buds also develop around week eight, but without taste pores (week 16), the fetus can’t taste the amniotic fluid surrounding it. Fun fact: amniotic fluid tastes like the most recent meal of the pregnant person, and it’s believed that gustatory likes and dislikes begin in the womb.
If development isn’t proceeding as it should, the pregnancy will end in spontaneous abortion, the term for miscarriages that occur within the first 20 weeks. Most statistics report that somewhere around 20 percent of recognized pregnancies (when people have already discovered they are pregnant) end in miscarriage, the vast majority of which occur in the first trimester. Most spontaneous abortions are caused by severe chromosomal abnormalities which halt fetal development. They can also be caused by ectopic pregnancies (when the fertilized egg implants in the fallopian tube) or heavy implantation bleeding, which can be caused by low levels of progesterone. Repeated miscarriages are relatively rare, only occurring in around five percent of people, and can indicate deeper underlying fertility issues like genetic predispositions to chromosomal abnormalities or advanced age of the carrier. Chance of miscarriage increases for pregnancies in people over 35, climbing to a 50 percent chance of spontaneous abortion after the age of 45.
Several genetic tests often occur in the first trimester to monitor fetal development, especially chromosomal abnormalities that may cause the parents to abort the pregnancy. A nuchal translucency screening occurs between weeks 11 and 14 to screen for chromosomal abnormalities and heart defects. An ultrasound is performed, and the nuchal fold (base of the neck) of the fetus is measured to assess the amount of fluid within. If the fetus has a large nuchal fold with high fluid levels, this may indicate chromosomal abnormalities like Down Syndrome. At this point, a blood test would be performed to assess parental levels of hCG and pregnancy-associated plasma protein A (PAPP-A). Low levels of PAPP-A, a hormone produced by the fetus and released into the carrier’s bloodstream, may further indicate chromosomal abnormalities and possible heart defects. The test hovers around 80 percent detection rate of Down Syndrome and other chromosomal abnormalities. If the results appear to indicate developmental issues, more invasive tests like amniocentesis and/or chorionic villus sampling may be performed for higher levels of accuracy. Many parents may choose to end the pregnancy if unprepared to deliver a child with possible special needs.
In the first trimester of pregnancy, if planning to carry the pregnancy to term, a person should begin taking prenatal vitamins, visit an obstetrician, renounce drugs and alcohol (including caffeine!) and avoid using tampons if spotting. Hurray! Now everyone is absolutely prepared to have a tiny human inside of them. I will be continuing on to trimesters two, three and delivery (yikes!) in future columns.
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