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2.9: Prenatal Assessment

  • Page ID
    184023
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    A number of assessments are suggested to women as part of their routine prenatal care to find conditions that may increase the risk of complications for the mother and fetus (Eisenberg et al., 1996). These can include blood and urine analyses and screening, and diagnostic tests for birth defects.

    Ultrasound is one of the main screening tests done in combination with blood tests. The ultrasound is a test in which sound waves are used to examine the fetus. There are two general types. Transvaginal ultrasounds are used in early pregnancy, while transabdominal ultrasounds are more common and used after 10 weeks of pregnancy (typically, 16 to 20 weeks). Ultrasounds are used to check the fetus for defects or problems. It can also find out the age of the fetus, location of the placenta, fetal position, movement, breathing and heart rate, amount of amniotic fluid, and number of fetuses. Most women have at least one ultra sound during pregnancy, but if problems are noted, additional ultrasounds may be recommended.

    A doctor examines the abdomen of a pregnant woman lying on a medical table.
    Figure \(\PageIndex{1}\). Preparing for an ultrasound. Image source.

    When diagnosis of a birth defect is necessary, ultrasounds help guide the more invasive diagnostic tests of amniocentesis and chorionic villus sampling. Amniocentesis is a procedure in which a needle is used to withdraw a small amount of amniotic fluid and cells from the sac surrounding the fetus and later tested (see Figure \(\PageIndex{2}\)).

    Diagram showing the components of the amniocentesis procedure. As guided by a live ultrasound, a syringe is used to penetrate the uterus and take a sample of the amniotic fluid without touching the fetus.
    Figure \(\PageIndex{2}\). Amniocentesis. Image source.

    Chorionic Villus Sampling is a procedure in which a small sample of cells is taken from the placenta and tested. Both amniocentesis and chorionic villus sampling have a risk of miscarriage, and consequently they are not done routinely.

    Note \(\PageIndex{1}\): Infertility and Reproductive Technology

    Infertility: Infertility affects about 10 to 15 percent of couples in the United States (Mayo Clinic, 2015). For men, the most common cause is low sperm production or a lack thereof, and for women, it is the failure to ovulate. Another common cause for women is pelvic inflammatory disease (PID), which is an infection of a woman's reproductive organs (Carroll, 2007). It is often a complication caused by an STD, such as chlamydia and gonorrhea, although other infections that are not sexually transmitted can also cause PID.

    Fertility treatment: The majority of infertility cases are treated using fertility drugs to increase ovulation, or with surgical procedures to repair the reproductive organs or remove scar tissue from the reproductive tract. In in vitro fertilization (IVF), eggs are removed from the woman and are fertilized outside her body. The fertilized egg is then reinserted in the woman's uterus. The success rate varies depending on the type of egg implanted, such as whether the egg was recently removed from the woman, used after being frozen, or donated from another woman. Success is also highly dependent on the age of the mother (See Figure \(\PageIndex{3}\).

    Plot of the percentage of pregnancies, live births, and single-infant live births resulting from in-vitro fertilization using non-donor eggs as a function of the mother's age. Percentages for all categories peak at around age 25 and begin to decline dramatically around age 38.
    Figure \(\PageIndex{3}\). Percentage of pregnancies, live births, and single-infant live births from IVF from fresh non-donor eggs. Source.

    Procedures that have higher success rates but are less common include gamete intra-fallopian tube transfer (GIFT), which involves implanting both sperm and ova into the fallopian tube, where fertilization is allowed to occur naturally (Carroll, 2007). Zygote intra-fallopian tube transfer (ZIFT) is another procedure in which sperm and ova are fertilized outside of the woman's body and the fertilized egg is then implanted in the fallopian tube. This allows the zygote to travel down the fallopian tube and embed in the lining of the uterus naturally. This procedure also has a higher success rate than IVF.


    This page titled 2.9: Prenatal Assessment is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Martha Lally and Suzanne Valentine-French via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.