Medications in Pregnancy and Labor - An Overview

Introduction:

Medications can profoundly impact pregnancy when consumed in any form. Pregnant women should always check with their gynecologist and avoid self-medication. Some drugs are known to cause birth defects, so discussing potential risks with the doctor before starting any new medication or changing your current one is important. Some medications can cause fetal distress when they are given during pregnancy, which can lead to miscarriage or premature delivery.

How Do Drugs Impact Pregnancy?

The drugs used in pregnancy and labor can impact the mother and the baby during all trimesters. The drugs used during the first trimester can produce congenital abnormalities. The period from the third to the eleventh week is at greater risk in pregnancy as organogenesis occurs. During the second and third trimesters, drugs can affect the growth and functional development of the fetus. If care is not taken, drugs can harm fetal tissues.

Various drugs used in pregnancy and labor are as follows-

Drugs Used in Pregnancy Are-

• Folic acid.

• Iron.

• Calcium.

• Antihypertensives.

• Diuretics.

Drugs Used in Labor Are-

• Oxytocin.

• Analgesic.

• Anticonvulsants.

• Anticoagulants.

What Are the Various Drugs Used in Pregnancy?

Drugs used in pregnancy are as follows-

1. Folic Acid

• Action- Stimulates normal erythropoiesis (production of red blood cells) and nucleoprotein synthesis.

• Preparation- Used as injections (intramuscular or subcutaneous) or tablets (oral).

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• Indications- Megaloblastic or macrocytic anemia during pregnancy to prevent fetal damage. Patients with intestinal malabsorption (may need parenteral administration).

• Contraindications- Untreated vitamin B12 deficiency.

• Adverse effects- Abdominal cramps, diarrhea, irritability, rashes, nausea, or bloating.

2. Iron (Ferrous Fumarate)

• Action- Provides elemental iron, an essential component in forming hemoglobin.

• Preparation- Used as injections (intramuscular) or tablets (oral).

• Indications- Iron deficiency or as a supplement during pregnancy. Patients are advised not to take tablets with milk or antacids.

• Contraindications- Primary hemolytic anemia, peptic ulcers, blood transfusions, or ulcerative colitis.

• Adverse effects- Metallic taste, nausea, vomiting, gastrointestinal irritation, staining of teeth, and black stools.

3. Calcium (Calcium Citrate)

• Action- To maintain calcium levels.

• Preparation- Used as oral tablets.

• Indications- As a supplement. Calcium levels must be monitored if the patient has mild renal impairment.

• Contraindications- Hypercalcemia (calcium level more than normal), hypophosphatemia (low level of phosphate in the blood), kidney stones, or cancer patients with bone metastasis.

• Adverse Effects- Headache, irritability, chalky taste, nausea, vomiting, or hypercalcemia.

4. Antihypertensives

The following categories of antihypertensives can be given during pregnancy-

• Alpha and Beta-blockers- Labetalol Hydrochloride.

• Calcium channel blockers- Nifedipine.

• Alpha-blockers- Methyldopa.

• Vasodilators- Hydralazine hydrochloride.

The following categories of antihypertensives are contraindicated in pregnancy as they can cause impaired fetal renal function, malformation, or IUGR (intrauterine growth restriction)-

• ACE inhibitors.

• Minoxidil.

• Sodium Nitroprusside.

• Diltiazem.

• Atenolol.

• Propranolol.

5. Diuretics

• Commonly used diuretics are-

  • Furosemide - is used in acute pulmonary edema, edema, or hypertension.

  • Tocolytic agents (Isoxsuprine Hydrochloride and Ritrodrine hydrochloride) - to prevent pre-term labor or inhibit uterine contractions.

• Diuretics are indicated in cases like-

  • Pregnancy-induced hypertension (PIH) with massive edema.

  • Severe anemia in pregnancy with heart failure and before blood transfusion.

  • Eclampsia with pulmonary edema.

  • As an adjunct to some antihypertensives.

What Are the Various Drugs Used in Labor?

Drugs used in labor are as follows-

Oxytocin- Oxytocins are drugs that can initiate contractions of the uterine muscles. The following types of oxytocins are used during labor-

• Oxytocin

  • Action- Responsible for uterine contractions and milk ejection by the breasts.

  • Indications- To induce labor or abortion, to initiate expulsion of hydatidiform mole, for oxytocin challenge test, stop bleeding after evacuation, prevent postpartum hemorrhage, and start milk ejection in breasts.

  • Contraindications- Contracted pelvis, hysterectomy, obstructed labor, cardiac diseases, abnormal uterine action, or hypovolemic state.

  • Adverse Effects- Hypotension, hypertonic uterine activity, fetal distress or death, uterine rupture, neonatal jaundice, water retention, and water intoxication.

• Ergot Derivatives

  • Action- Responsible for uterine contractions and decreased bleeding.

  • Indications- To stop uterine bleeding after abortion or delivery.

  • Contraindications- Plural pregnancy, cardiac diseases, pre-eclampsia, or eclampsia.

  • Adverse Effects- Rise in blood pressure due to vasoconstriction.

• Prostaglandins are available as Prostin E2 or PG E2 (Dinoprostone), Prostin F2 alpha or PG F2 (Dinoprostodine), and PG E1 or Misoprostol.

  • Indications- For induction of abortion during the second trimester, the expulsion of hydatidiform mole, labor induction, acceleration of labor, stopping bleeding from open uterine sinuses, or cervical ripening.

  • Contraindications- Hypersensitivity, uterine fibroids, cervical stenosis, or pelvic inflammatory disease (PID).

  • Adverse Effects- Headache, dizziness, hypertension, leg cramps, or joint edema.

1. Analgesics- Analgesics can help during the first stage of labor in cervical dilatation, symptomatic relief from pain. Some commonly used painkillers during labor are-

• Valethamate Bromide (Epidosin).

• Tramadol Hydrochloride.

2. Anticonvulsants (Magnesium Sulphate)

• Action- Reduces neuromuscular irritability and intracranial edema, improve uterine blood supply, and depressant action on uterine muscles.

• Indications- Lowers seizure threshold in women with pregnancy-induced hypertension.

• Contraindications- Heart block, impaired renal function, or active progressing labor.

• Adverse Effects- Depression of the central nervous system or muscular paresis in the mother. Tachycardia or hypoglycemia in the fetus.

3. Anticoagulants

• Action- Promotes hepatic formation of II, VII, IX, and X clotting factors.

• Indications- To treat and prevent bleeding disorders, it helps the liver to produce clotting factors.

• Contraindications- Hypersensitivity.

• Adverse Effects- Pain, edema, allergic reaction, or hyperbilirubinemia.

What Are the Effects of Maternal Medications on Fetus?

• During early embryogenesis, the drugs taken by the mother reach the fetus by diffusion through the uterine secretions.

• Some drugs can cause congenital anomalies.

• From the second to the twelfth week (organogenesis), drugs can cause severe damage. Depending on the route, time, and dose of exposure, it may result in gross congenital abnormalities and even death of the fetus.

• From the second trimester, drug transfer occurs through the placenta. The drug metabolism may be affected by the increase in plasma steroids, increased uteroplacental blood flow, increased placental surface area & decreased thickness of placental membrane leading to increased drug transfer.

• Fetotoxic or teratogenic drugs are prescribed only when the benefits are more important than the potential risks.

Conclusion

A woman should only be given drugs during pregnancy and labor after calculating the possible risks and their effect on maternal and fetal outcomes. In addition, the benefits of these drugs must outweigh the adverse effects.