Intrauterine exposure to environmental toxins in pregnancy has the potential to cause adverse effects on the development of the embryo/fetus and to cause pregnancy complications. Air pollution has been associated with low birth weight infants. Conditions of particular severity in pregnancy include mercury poisoning and lead poisoning. To minimize exposure to environmental toxins, the "American College of Nurse-Midwives" recommends: checking whether the home has lead paint, washing all fresh fruits and vegetables thoroughly and buying organic produce, and avoiding cleaning products labeled "toxic" or any product with a warning on the label.

Pregnant women can also be exposed to toxins in the workplace, including airborne particles. The effects of wearing N95 filtering facepiece respirators are similar for pregnant women as non-pregnant women, and wearing a respirator for one hour does not affect the fetal heart rate.

The use of recreational drugs in pregnancy can cause various pregnancy complications.

- Ethanol during pregnancy can cause fetal alcohol syndrome and fetal alcohol spectrum disorder. Studies have shown that light to moderate drinking during pregnancy might not pose a risk to the fetus, although no amount of alcohol during pregnancy can be guaranteed to be absolutely safe.

- Tobacco smoking during pregnancy can cause a wide range of behavioral, neurological, and physical difficulties. Smoking during pregnancy causes twice the risk of premature rupture of membranes, placental abruption and placenta previa. Smoking is associated with 30% higher odds of preterm birth.

- Prenatal cocaine exposure is associated with premature birth, birth defects and attention deficit disorder.

- Prenatal methamphetamine exposure can cause premature birth and congenital abnormalities. Short-term neonatal outcomes show small deficits in infant neurobehavioral function and growth restriction. Long-term effects in terms of impaired brain development may also be caused by methamphetamine use.

- Cannabis in pregnancy has been shown to be teratogenic in large doses in animals, but has not shown any teratogenic effects in humans.

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.

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).

Levels of hemoglobin are lower in the third trimesters. According to the United Nations (UN) estimates, approximately half of pregnant women suffer from anemia worldwide. Anemia prevalences during pregnancy differed from 18% in developed countries to 75% in South Asia.

Treatment varies due to the severity of the anaemia, and can be used by increasing iron containing foods, oral iron tablets or by the use of parenteral iron.

While lifestyle factors have been associated with increased risk for miscarriage in general, and are usually not listed as specific causes for RPL, every effort should be made to address these issues in patients with RPL. Of specific concern are chronic exposures to toxins including smoking, alcohol, and drugs.

If the likely cause of recurrent pregnancy loss can be determined treatment is to be directed accordingly. In pregnant women with a history of recurrent miscarriage, anticoagulants seem to increase the live birth rate among those with antiphospholipid syndrome and perhaps those with congenital thrombophilia but not in those with unexplained recurrent miscarriage. One study found that in many women with chronic endometritis, "fertility was restored after appropriate antibiotic treatment."

There are currently no treatments for women with unexplained recurrent pregnancy loss. The majority of patients are counseled to try to conceive again, and chances are about 60% that the next pregnancy is successful without treatment. However, each additional loss worsens the prognostic for a successful pregnancy and increases the psychological and physical risks to the mother. Aspirin has no effect in preventing recurrent miscarriage in women with unexplained recurrent pregnancy loss. Immunotherapy has not been found to help. There is currently one drug in development, NT100, which is in clinical trials for the treatment of unexplained recurrent miscarriage. The study investigates the role of NT100 in improving maternal-fetal tolerance for women with unexplained recurrent miscarriage

In certain chromosomal situations, while treatment may not be available, in vitro fertilization with preimplantation genetic diagnosis may be able to identify embryos with a reduced risk of another pregnancy loss which then would be transferred. However, in vitro fertilization does not improve maternal-fetal tolerance imbalances.

Close surveillance during pregnancy is generally recommended for pregnant patients with a history of recurrent pregnancy loss. Even with appropriate and correct treatment another pregnancy loss may occur as each pregnancy develops its own risks and problems.

Some disorders and conditions can mean that pregnancy is considered high-risk (about 6-8% of pregnancies in the USA) and in extreme cases may be contraindicated. High-risk pregnancies are the main focus of doctors specialising in maternal-fetal medicine.

Serious pre-existing disorders which can reduce a woman's physical ability to survive pregnancy include a range of congenital defects (that is, conditions with which the woman herself was born, for example, those of the heart or , some of which are listed above) and diseases acquired at any time during the woman's life.

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

Being pregnant decreases the risk of relapse in multiple sclerosis; however, during the first months after delivery the risk increases. Overall, pregnancy does not seem to influence long-term disability. Multiple sclerosis does not increase the risk of congenital abnormality or miscarriage.

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.

When ectopic pregnancies are treated, the prognosis for the mother is very good in Western countries; maternal death is rare, but most fetuses die or are aborted. For instance, in the UK, between 2003 and 2005 there were 32,100 ectopic pregnancies resulting in 10 maternal deaths (meaning that 1 in 3,210 women with an ectopic pregnancy died).

In the developing world, however, especially in Africa, the death rate is very high, and ectopic pregnancies are a major cause of death among women of childbearing age.

In pregnancy, changes in the levels of female sex hormones, such as estrogen, make a woman more likely to develop candidal vulvovaginitis. During pregnancy, the "Candida" fungus is more prevalent (common), and recurrent infection is also more likely. There is no clear evidence that treatment of asymptomatic candidal vulvovaginitis in pregnancy reduces the risk of preterm birth. Candidal vulvovaginitis in pregnancy should be treated with intravaginal clotrimazole or nystatin for at least 7 days.

Taking aspirin is associated with a 1% to 5% reduction in pre-eclampsia and a 1% to 5% reduction in premature births in women at high risk. The World Health Organization recommends low-dose aspirin for the prevention of pre-eclampsia in women at high risk and recommends it be started before 20 weeks of pregnancy. The United States Preventive Services Task Force recommends a low-dose regimen for women at high risk beginning in the 12th week. Benefits are less if started after 16 weeks.

In low-risk pregnancies, the association between cigarette smoking and a reduced risk of pre-eclampsia has been consistent and reproducible across epidemiologic studies. High-risk pregnancies (those with pregestational diabetes, chronic hypertension, history of pre-eclampsia in a previous pregnancy, or multifetal gestation) showed no significant protective effect. The reason for this discrepancy is not definitively known; research supports speculation that the underlying pathology increases the risk of preeclampsia to such a degree that any measurable reduction of risk due to smoking is masked. However, the damaging effects of smoking on overall health and pregnancy outcomes outweighs the benefits in decreasing the incidence of preeclampsia. It is recommended that smoking be stopped prior to, during and after pregnancy.

Studies suggest that marijuana use in the months prior to or during the early stages of pregnancy may interfere with normal placental development and consequently increase the risk of preeclampsia.

Extrauterine pregnancies are non-viable and can be fatal to the mother if left untreated. The mortality rate for the extrauterine pregnancy is approximately 35%.

Heterotopic pregnancy is treated with surgical removal of the ectopic gestation by salpingectomy or salpingostomy. Expectant management has been successfully applied in select cases. Successful salpingocentesis has also been reported.

Because pregnancy is outside the uterus, abdominal pregnancy serves as a model of human male pregnancy or for females who lack a uterus, although such pregnancy would be dangerous.

Cases of combined simultaneous abdominal and intrauterine pregnancy have been reported.

A woman may elect to discontinue alcohol once she knows that she is pregnant. A woman can have serious symptoms that accompany alcohol withdrawal during pregnancy. These symptoms can be treated during pregnancy with benzodiazepine.

Ideally the management of abdominal pregnancy should be done by a team that has medical personnel from multiple specialties. Potential treatments consist of surgery with termination of the pregnancy (removal of the fetus) via laparoscopy or laparotomy, use of methotrexate, embolization, and combinations of these. Sapuri and Klufio indicate that conservative treatment is also possible if the following criteria are met: 1. there are no major congenital malformations; 2. the fetus is alive; 3. there is continuous hospitalization in a well-equipped and well-staffed maternity unit which has immediate blood transfusion facilities; 4. there is careful monitoring of maternal and fetal well being; and 5. placental implantation is in the lower abdomen away from the liver and spleen. The choice is largely dictated by the clinical situation. Generally, treatment is indicated when the diagnosis is made; however, the situation of the advanced abdominal pregnancy is more complicated.

True cervical pregnancies tend to abort; if, however, the pregnancy is located higher in the canal and the placenta finds support in the uterine cavity it can go past the first trimester. With the placenta being implanted abnormally extensive vaginal bleeding can be expected at time of delivery and placental removal. While early cervical pregnancies may abort spontaneously or can be managed with excision, D&C, suturing, electrocautery, and tamponading, by medication such as methotrexate, and/or by uterine artery embolization, a more advanced pregnancy may require a hysterectomy to control bleeding. The more advanced the pregnancy the higher the risk for a major bleeding necessitating a hysterectomy.

On a very rare occasion, a cervical pregnancy results in the birth of a live baby, typically the pregnancy is in the upper part of the cervical canal and manages to extend into the lower part of the uterine cavity.

A cervical pregnancy can develop together with a normal intrauterine pregnancy; such a heterotopic pregnancy will call for expert management as to not to endanger the intrauterine pregnancy.

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.

Starting in 1981, the surgeon general of the United States started releasing a warning asking pregnant women to abstain from alcohol for the remainder of 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.

Patients with an ectopic pregnancy are generally at higher risk for a recurrence, however, there are no specific data for patients with an interstitial pregnancy. When a new pregnancy is diagnosed it is important to monitor the pregnancy by transvaginal sonography to assure that is it properly located, and that the surgically repaired area remains intact. Cesarean delivery is recommended to avoid uterine rupture during labor.