OB: PRECONCEPTION MEDICAL DISEASES AND TERATOGENS Flashcards
Why does a patient with hypothyroidism need an increase in their levothyroxine in pregnancy?
During pregnancy, estrogen induces the production of proteins, including thyroid-binding globulin, which binds T4 and T3. A normal patient will see alterations in TSH and T4 as the thyroid axis responds to meet the needs of mom and baby—the decrease in free T4 and T3 is met with increased production of T4 and T3 to maintain euthyroid levels. In a patient with hypothyroidism, in which a fixed dose of thyroid hormone is provided through medication—levothyroxine—and not the thyroid axis, there is no compensatory increase in thyroid hormones in response to increased thyroid-binding globulin, resulting in relative hypothyroidism. The provider should anticipate the need to increase the levothyroxine dose (usually a 25% increase above the baseline dose at the start of pregnancy) and monitor TSH more regularly (every 4–6 weeks).
How do we treat hyperthyroid in pregnancy?
Medical therapy for hyperthyroidism includes propylthiouracil (PTU) and methimazole. These are both thionamides, but PTU is associated with more hepatotoxicity but less teratogenicity.
Because teratogens have the most effect in the first trimester, current guidelines say to treat with PTU in the first trimester, then switch to methimazole in the second and third trimesters.
They are likely equivalent, but there aren’t enough data to change the guidelines. Ancient Teratogenic Medications. These medications have not been used for decades but mark the necessity for identifying teratogenic medications.
What historic medications with teratogenicity do you need to know?
Diethylstilbesterol (DES) was given to women with “at-risk pregnancies.” It led to reproductive malformations and cancer of the vagina. Thalidomide was used as a sedative during pregnancy. It causes limb deformities (short or absent).
When does morning sickness begin to wane?
By week 16
Women with hyperemesis gravidarum are at risk for what?
Starvation Ketosis and profound hypovolemia
When do we see excessive morning sickness?
Multifetal gestation and molar pregnancies
What antiemetics do we start with?
ginger in practice. On exam: Doxylamine succinate and pyridoxine (vitamin B6) are the safest antiemetics but not the most effective antiemetic combo
What increases risk for DVT?
Pregnancy is a risk factor for deep-vein thrombosis (DVT). Estrogen induces the liver to synthesize extra clotting factors, and the gravid uterus compresses the inferior vena cava, leading to stasis.
How do we treat DVTs in pregnancy?
Whether the DVT develops prior to or during pregnancy, avoidwarfarin.If given in the first trimester, it causes skeletal abnormalities and nasal hypoplasia. Low molecular weight heparin (LMWH) is administered subcutaneously and should be considered the only treatment for DVT/PE during pregnancy. NOACs have not been studied well enough to be recommended during pregnancy
What do you need to know for a mom with bipolar?
When treating bipolar disorder, watch out for valproic acid and lithium. Valproic acid causes neural tube defects if taken during the first trimester. Lithium causes Ebstein’s anomaly, a structural defect in the right atrium and tricuspid valve; however, it is so rare that lithium is not listed as a major teratogen and should be continued throughout pregnancy if indicated. More commonly, third-trimester exposure to lithium causes neonatal adaptive disorder—poor motor strength, including suckling—that spontaneously resolves in 1–2 weeks. Atypical antipsychotic medications are used in pregnancy despite limited safety data. Monitor for macrosomia.
Valproic acid puts fetus at increased risk of…
neural tube defects
Lithium increases fetus’s risk for…
Ebsteins anomaly
What is the stance on SSRIs and SNRIs in pregnancy?
Safe, do not stop. Maybe floppy baby in 3rd trimester
What should you monitor for with atypical antipsychotics?
Macosomia
Why do we have to be careful with antiepileptic drugs?
Major congenital malformations, including neural tube defects, cardiac anomalies, orofacial clefts, skeletal defects (particularly club foot), and hypospadias, interfere with organ structure or function and often require surgical intervention or repair. Major congenital malformations may result from fetal exposure to AEDs, especially during the first trimester—most malformations occur between 3 and 10 weeks’ fetal age.
