Drugs used during pregnancy can have temporary or permanent effects on the fetus. Anything (including drugs) that can cause permanent deformities in the fetus are labeled as teratogens. In the U.S., drugs were classified into categories A, B, C, D and X based on the Food and Drug Administration (FDA) rating system to provide therapeutic guidance based on potential benefits and fetal risks. Drugs, including some multivitamins, that have demonstrated no fetal risks after controlled studies in humans are classified as Category A. On the other hand, drugs like thalidomide with proven fetal risks that outweigh all benefits are classified as Category X.

Nutrition during pregnancy is important to ensure healthy growth of the fetus. Nutrition during pregnancy is different from the non-pregnant state. There are increased energy requirements and specific micronutrient requirements. Women benefit from education to encourage a balanced energy and protein intake during pregnancy. Some women may need professional medical advice if their diet is affected by medical conditions, food allergies, or specific religious/ ethical beliefs.

Adequate periconceptional (time before and right after conception) folic acid (also called folate or Vitamin B) intake has been shown to decrease the risk of fetal neural tube defects, such as spina bifida. The neural tube develops during the first 28 days of pregnancy, a urine pregnancy test is not usually positive until 14 days post-conception, explaining the necessity to guarantee adequate folate intake before conception. Folate is abundant in green leafy vegetables, legumes, and citrus. In the United States and Canada, most wheat products (flour, noodles) are fortified with folic acid.

DHA omega-3 is a major structural fatty acid in the brain and retina, and is naturally found in breast milk. It is important for the woman to consume adequate amounts of DHA during pregnancy and while nursing to support her well-being and the health of her infant. Developing infants cannot produce DHA efficiently, and must receive this vital nutrient from the woman through the placenta during pregnancy and in breast milk after birth.

Several micronutrients are important for the health of the developing fetus, especially in areas of the world where insufficient nutrition is common. Women living in low and middle income countries are suggested to take multiple micronutrient supplements containing iron and folic acid. These supplements have been shown to improve birth outcomes in developing countries, but do not have an effect on perinatal mortality. Adequate intake of folic acid, and iron is often recommended. In developed areas, such as Western Europe and the United States, certain nutrients such as Vitamin D and calcium, required for bone development, may also require supplementation. Vitamin E supplementation has not been shown to improve birth outcomes. Zinc supplementation has been associated with a decrease in preterm birth, but it is unclear whether it is causative. Daily iron supplementation reduces the risk of maternal anemia. Studies of routine daily iron supplementation for pregnant women found improvement in blood iron levels, without a clear clinical benefit. The nutritional needs for women carrying twins or triplets. are higher than those of women carrying one baby.

Women are counseled to avoid certain foods, because of the possibility of contamination with bacteria or parasites that can cause illness. Careful washing of fruits and raw vegetables may remove these pathogens, as may thoroughly cooking leftovers, meat, or processed meat. Unpasteurized dairy and deli meats may contain "Listeria," which can cause neonatal meningitis, stillbirth and miscarriage. Pregnant women are also more prone to "Salmonella" infections, can be in eggs and poultry, which should be thoroughly cooked. Cat feces and undercooked meats may contain the parasite Toxoplasma gondii and can cause toxoplasmosis. Practicing good hygiene in the kitchen can reduce these risks.

Women are also counseled to eat seafood in moderation and to eliminate seafood known to be high in mercury because of the risk of birth defects. Pregnant women are counseled to consume caffeine in moderation, because large amounts of caffeine are associated with miscarriage. However, the relationship between caffeine, birthweight, and preterm birth is unclear.

Early treatment of an ectopic pregnancy with methotrexate is a viable alternative to surgical treatment which was developed in the 1980s. If administered early in the pregnancy, methotrexate terminates the growth of the developing embryo; this may cause an abortion, or the developing embryo may then be either resorbed by the woman's body or pass with a menstrual period. Contraindications include liver, kidney, or blood disease, as well as an ectopic embryonic mass > 3.5 cm.

Also, it may lead to the inadvertent termination of an undetected intrauterine pregnancy, or severe abnormality in any surviving pregnancy. Therefore, it is recommended that methotrexate should only be administered when hCG has been serially monitored with a rise less than 35% over 48 hours, which practically excludes a viable intrauterine pregnancy.

If bleeding has already occurred, surgical intervention may be necessary. However, whether to pursue surgical intervention is an often difficult decision in a stable patient with minimal evidence of blood clot on ultrasound.

Surgeons use laparoscopy or laparotomy to gain access to the pelvis and can either incise the affected Fallopian and remove only the pregnancy (salpingostomy) or remove the affected tube with the pregnancy (salpingectomy). The first successful surgery for an ectopic pregnancy was performed by Robert Lawson Tait in 1883. It is estimated that an acceptable rate of PULs that eventually undergo surgery is between 0.5 and 11%.

Autotransfusion of a woman's own blood as drained during surgery may be useful in those who have a lot of bleeding into their abdomen.

Published reports that a re-implanted embryo survived to birth were debunked as false.

The apprehension is not necessarily data driven and is a cautionary response to the lack of clinical studies in pregnant women. The indication is a trade-off between the adverse effects of the drug, the risks associated with intercurrent diseases and pregnancy complications, and the efficiency of the drug to prevent or ameliorate such risks. In some cases, the use of drugs in pregnancy carries benefits that outweigh the risks. For example, high fever is harmful for the fetus in the early months, thus the use of paracetamol (acetaminophen) is generally associated with lower risk than the fever itself. Similarly, diabetes mellitus during pregnancy may need intensive therapy with insulin to prevent complications to mother and baby. Pain management for the mother is another important area where an evaluation of the benefits and risks is needed. NSAIDs such as Ibuprofen and Naproxen are probably safe for use for a short period of time, 48–72 hours, once the mother has reached the second trimester. If taking aspirin for pain management the mother should never take a dose higher than 100 mg.

The World Health Organization recommends that women with severe hypertension during pregnancy should receive treatment with anti-hypertensive agents. Severe hypertension is generally considered systolic BP of at least 160 or diastolic BP of at least 110. Evidence does not support the use of one anti-hypertensive over another. The choice of which agent to use should be based on the prescribing clinician's experience with a particular agent, its cost, and its availability. Diuretics are not recommended for prevention of preeclampsia and its complications. Labetolol, Hydralazine and Nifedipine are commonly used antihypertensive agents for hypertension in pregnancy. ACE inhibitors and angiotensin receptor blockers are contraindicated as they affect fetal development.

The goal of treatment of severe hypertension in pregnancy is to prevent cardiovascular, kidney, and cerebrovascular complications. The target blood pressure has been proposed to be 140–160 mmHg systolic and 90–105 mmHg diastolic, although values are variable.

The intrapartum and postpartum administration of magnesium sulfate is recommended in severe pre-eclampsia for the prevention of eclampsia. Further, magnesium sulfate is recommended for the treatment of eclampsia over other anticonvulsants. Magnesium sulfate acts by interacting with NMDA receptors.

The goal of antiretroviral use during pregnancy is to reduce the risk of transmission of HIV from mother to child. It is important to choose medications that are safe for the mother and the fetus and which are effective at decreasing the total viral load. Some studies have shown an increase in stillbirths, preterm delivery, and delayed fetal growth in women using high doses of antiretroviral drugs during pregnancy. However, the overall benefits of ART are believed to outweigh the risks and all women are encouraged to use ART for the duration of their pregnancy.

Due to physiological changes in the body during pregnancy, it may be necessary to alter the dosing of medications so that they remain effective. Generally, the dose or the frequency of dosing are increased to account for these changes.

The recommended ART regimen for HIV-positive pregnant women consists of drugs from 4 different classes of medications listed below. In the United States, the favored regimen is a three-drug regimen where the first two drugs are NRTIs and the third is either a protease inhibitor, an integrase inhibitor, or an NNRTI.

- Nucleoside reverse transcriptase inhibitors (NRTIs) are considered the "backbone" of ART and 2 medications are generally used in combination. Due to its known safety profile and extensive use in pregnant patients, zidovudine-lamivudine (ZDV/3TC) is the preferred choice as the NRTI backbone. Zidovudine may worsen anemia, so patients with anemia are advised to use an alternative agent. For women who are coinfected with Hepatitis B, tenofovir with either emtricitabine or lamivudine is the preferred NRTI backbone. NRTI use may cause lactic acidosis in some women, so it is important to monitor patients for this complication. Deaths from lactic acidosis and liver failure have been associated with the use of two NRTIs, stavudine and didanosine (Zerit and Videx, respectively); therefore, combinations involving these drugs should be avoided in pregnancy.

- Protease inhibitors (PIs) have been studied extensively in pregnancy and are therefore the preferred third drug in the regimen. Atazanavir-ritonavir and darunavir-ritonavir are two of the most common PIs used during pregnancy. There is conflicting data regarding their association with preterm births, so women who are at a high risk for premature delivery are advised not to use PIs. Some PIs have been associated with hyperglycemia but is unclear whether they add to the risk of developing gestational diabetes. Some PIs have been noted to cause hyperbilirubinemia and nausea, so these side effects should be monitored for closely.

- Integrase inhibitors (IIs) are generally the third drug in the regimen when a PI cannot be used. They rapidly reduce the viral load and for this reason, they are often used in women who are diagnosed with HIV late in the pregnancy. Raltegravir is the most common II used.

- Non-nucleoside reverse transcriptase inhibitors (NNRTIs), the most popular being efavirenz and nevirapine, may be used during pregnancy. However, there are significant toxicities associated with their use, making them a less desirable option.

- Efavirenz (brand name Sustiva, and a component of the combination drug Atripla) is classified as a category D drug by the US Food and Drug Administration indicating there are risks associated with its use during pregnancy. In a study analyzing the use of the drug in pregnant women, 2.3% of births were associated with birth defects. However, a systematic review of the safety of efavirenz use in humans during the first trimester found no increase in birth defects among women using the drug. Given the uncertain potential for risk the U.S. DHHS recommends against using efavirenz in the first trimester of pregnancy or in women who may become pregnant. They instead recommend a protease inhibitor based regimen with lopinavir or atazanavir. However, to simplify regimens and provide a uniform recommendation for HIV-infected individuals during pregnancy, the WHO continues to recommend efavirenz as a first line agent for HIV positive women. Women using efavirenz prior to their pregnancy may continue with the drug as it is more dangerous to stop or change medications during pregnancy because this can result in improper control of the viral load.

- Nevirapine (trade name Viramune) increases the risk of very serious liver damage in women with CD4 counts greater than 250 cells/mm . It is generally avoided in pregnant women. Women taking nevirapine safely prior to pregnancy may continue with the medication because nevirapine-related liver damage has not been seen in women previously using the medication.

U.S. Code of Federal Regulations requires that certain drugs and biological products must be labelled very specifically with respect to their effects on pregnant populations, including a definition of a "pregnancy category." These rules are enforced by the Food and Drug Administration (FDA). The FDA does not regulate labelling for all hazardous and non-hazardous substances and some potentially hazardous substances are not assigned a pregnancy category.

Australia’s categorisations system takes into account the birth defects, the effects around the birth or when the mother gives birth, and problems that will arise later in the child's life caused from the drug taken. The system places them into a category of their severity that the drug could cause to the infant when it crosses the placenta(Australian Government, 2014).

This procedure involves the tearing of the dividing membrane between fetuses such that the amniotic fluid of both twins mixes under the assumption that pressure is different in either amniotic sac and that its equilibration will ameliorate progression of the disease. It has not been proven that pressures are different in either amniotic sac. Use of this procedure can preclude use of other procedures as well as make difficult the monitoring of disease progression. In addition, tearing the dividing membrane has contributed to cord entanglement and demise of fetuses through physical complications.

This procedure involves removal of amniotic fluid periodically throughout the pregnancy under the assumption that the extra fluid in the recipient twin can cause preterm labor, perinatal mortality, or tissue damage. In the case that the fluid does not reaccumulate, the reduction of amniotic fluid stabilizes the pregnancy. Otherwise the treatment is repeated as necessary. There is no standard procedure for how much fluid is removed each time. There is a danger that if too much fluid is removed, the recipient twin could die. This procedure is associated with a 66% survival rate of at least one fetus, with a 15% risk of cerebral palsy and average delivery occurring at 29 weeks gestation.

Vitamin A plays a role in the immune system and is a low-cost intervention that has been suggested to help with preventing mother-to-child transmission of HIV. A Cochrane review summarised the evidence of five trials conducted in Malawi, South Africa, Tanzania and Zimbabwe between 1995 and 2005, where none of the participants received antiretroviral therapy. They found that giving vitamin A supplementation to pregnant women or to women after they delivered a baby probably has little or no effect on mother-to-child transmission of HIV. The intervention has been largely suspended by antiretroviral therapy.

These have been ranked by the UK's National Institute for Health and Clinical Excellence:

- First line

- Intrauterine device with progesterone

- Second Line

- Tranexamic acid an antifibrinolytic agent

- Nonsteroidal anti-inflammatory drugs (NSAIDs).

- Combined oral contraceptive pills to prevent proliferation of the endometrium

- Third line

- Oral progestogen (e.g. norethisterone), to prevent proliferation of the endometrium

- Injected progestogen (e.g. Depo provera)

- Other options

- Gonadotropin-releasing hormone agonist

Aside from the social distress of dealing with a prolonged and heavy period, over time the blood loss may prove to be greater than the body iron reserves or the rate of blood replenishment, leading to anemia. Symptoms attributable to the anemia may include shortness of breath, tiredness, weakness, tingling and numbness in fingers and toes, headaches, depression, becoming cold more easily, and poor concentration.

A number of antiemetics are effective and safe in pregnancy including: pyridoxine/doxylamine, antihistamines (such as diphenhydramine), metoclopramide, and phenothiazines (such as promethazine). With respect to effectiveness it is unknown if one is superior to another. In the United States and Canada, the doxylamine-pyridoxine combination (as Diclegis in US and Diclectin in Canada) is the only approved pregnancy category "A" prescription treatment for nausea and vomiting of pregnancy.

Ondansetron may be beneficial, but there are some concerns regarding an association with cleft palate, and there is little high quality data. Metoclopramide is also used and relatively well tolerated. Evidence for the use of corticosteroids is weak.

A septum can be resected with surgery. Hysteroscopic removal of a uterine septum is generally the preferred method, as the intervention is relatively minor and safe in experienced hands. A follow-up imaging study should demonstrate the removal of the septum.

Tactile cold scissor metroplasty was described as a back technique for hysteroscopic challenges that interfere with proper visualization or uterine distention

It is not considered necessary to remove a septum that has not caused problems, especially in women who are not considering pregnancy. There is controversy over whether a septum should be removed prophylactically to reduce the risk of pregnancy loss prior to a pregnancy or infertility treatment.

The data presented is for comparative and illustrative purposes only, and may have been superseded by updated data.

Some studies support the use of ginger, but overall the evidence is limited and inconsistent. Safety concerns have been raised regarding its anticoagulant properties.

Vaccinating the majority of the population is effective at preventing congenital rubella syndrome.

There is no cure for FASD, but treatment is possible. Because CNS damage, symptoms, secondary disabilities, and needs vary widely by individual, there is no one treatment type that works for everyone.

Cannabis consumption in pregnancy might be associated with restrictions in growth of the fetus, miscarriage, and cognitive deficits. The American Congress of Obstetricians and Gynecologists recommended that cannabis use be stopped before and during pregnancy, Cannabis is the most commonly used illicit substance

among pregnant women.

Although it is difficult to draw firm conclusions, there is some evidence that prenatal exposure to marijuana may be associated with deficits in language, attention, cognitive performance, and delinquent behaviors. THC exposure in rats during the prenatal developmental phase may cause epigenetic changes in gene expression, but there is limited knowledge about the risk for psychiatric disorders because of ethical barriers to studying the developing human brain. While animal studies cannot take into account factors that could influence the effects of cannabis on human maternal exposure, such as environmental and social factors, a 2011 review of rodent studies by Campolongo "et al." said there was "... increasing evidence from animal studies showing that cannabinoid drugs ... induce enduring neurobehavioral abnormalities in the exposed offspring ..." Campolongo "et al." added that "clinical studies report hyperactivity, cognitive impairments and altered emotionality in humans exposed in utero to cannabis". Martin "et al." investigated recent trends in substance abuse treatment admissions for cannabis use in pregnancy in the US, based on Treatment Episodes Data Set (TEDS) from 1992 to 2012, and discovered that, while the proportion of treatment admissions for pregnant women was stable (about 4%), the admissions for women who were pregnant and reported any marijuana use grew from 29% to 43%. A 2015 review found that cannabis use by pregnant mothers impaired brain maturation in their children, and that it also predisposed their children to neurodevelopmental disorders.

The pregnancy category of a medication is an assessment of the risk of fetal injury due to the pharmaceutical, if it is used as directed by the mother during pregnancy. It does "not" include any risks conferred by pharmaceutical agents or their metabolites in breast milk.

Every drug has specific information listed in its product literature. The British National Formulary used to provide a table of drugs to be avoided or used with caution in pregnancy, and did so using a limited number of key phrases, but now Appendix 4 (which was the Pregnancy table) has been removed. Appendix 4 is now titled "Intravenous Additives". However, information that was previously available in the former Appendix 4 (pregnancy) and Appendix 5 (breast feeding) is now available in the individual drug monographs.

The role of the endocannabinoid system (ECS) in female fertility has long been suspected and studied. Most studies through 2013 linking development of the fetus and cannabis show effects of consumption during the gestational period, but abnormalities in the endocannabinoid system during the phase of placental development are also linked with problems in pregnancy. According to Sun and Dey (2012), endocannabinoid signaling plays a role in "female reproductive events, including preimplantation embryo development, oviductal embryo transport, embryo implantation, placentation, and parturition". Karusu "et al" (2011) said that a "clear correlation ... in the actual reproductive tissues of miscarrying versus healthy women has yet to be established. However, the adverse effects of marijuana smoke and THC on reproductive functions point to processes that are modulated by ECS."

Keimpema and colleagues (2011) said, "Prenatal cannabis exposure can lead to growth defects during formation of the nervous system"; "[c]annabis impacts the formation and functions of neuronal circuitries by targeting cannabinoid receptors ... By indiscriminately prolonging the "switched-on" period of cannabinoid receptors, cannabis can hijack endocannabinoid signals to evoke molecular rearrangements, leading to the erroneous wiring of neuronal networks". A report prepared for the Australian National Council on Drugs concluded cannabis and other cannabinoids are contraindicated in pregnancy as they may interact with the endocannabinoid system.

Psychoactive drugs are frequently tried on those with FASD as many FASD symptoms are mistaken for or overlap with other disorders, most notably ADHD.

Congenital rubella syndrome (CRS) can occur in a developing fetus of a pregnant woman who has contracted rubella, usually in the first trimester. If infection occurs 0–28 days before conception, the infant has a 43% risk of being affected. If the infection occurs 0–12 weeks after conception, the risk increases to 51%. If the infection occurs 13–26 weeks after conception, the risk is 23% of the infant being affected by the disease. Infants are not generally affected if rubella is contracted during the third trimester, or 26–40 weeks after conception. Problems rarely occur when rubella is contracted by the mother after 20 weeks of gestation and continues to disseminate the virus after birth.

It was discovered in 1941 by Australian Norman McAlister Gregg.