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.

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.

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).

The data presented is for comparative and illustrative purposes only, and may have been superseded by updated data.

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.

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 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 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.

One way to address problems with uncertainty about cocaine's effects due to confounding factors is to use animal models; these allow experimenters to study the effects at specific doses and times. Studies have used mice, other rodents, rabbits, and primates.

However, differences between species' physiology and gestation times mean findings in animals may not apply to humans. Mice, rats, and rabbits have shorter gestational times, so experimenters must continue giving drugs after they are born to more closely model human gestation; however this introduces more differences. Animals and humans metabolize drugs at different rates, and drugs that are highly teratogenic in animals may not be in humans and vice versa. Animals cannot be used to measure differences in abilities such as reasoning that are only found in humans.

Animal studies in various species have found that cocaine impacts brain structure, function, and chemistry, and causes long-term changes at the molecular, cellular, and behavioral levels. In research studies on pregnant rats, injected cocaine did less damage to cells than injected nicotine, and more recovery occurred between doses. Adult rats that were exposed to cocaine prenatally have deficits in learning, memory, and motor skills, and may have abnormalities in dopamine processing. Animal research has also shown that offspring of males that used cocaine while their sperm were forming may go on to have abnormalities later in life.

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.

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.

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.

Studies have returned widely varying reports of the effects of PCE: some claim the physical disabilities are severe and generalized, others find specific effects, others none all.

The timing of the dose of the drug is an important determinant of outcome, in addition to how much is used, for how long, and what kind of care is rendered after birth. Drug use in the first trimester is the most harmful to the fetus in terms of neurological and developmental outcome. The effects of PCE later in a child's life are poorly understood; there is little information about the effects of "in utero" cocaine exposure on children over age five. Some studies have found PCE-related differences in height and weight while others have not; these differences are generally gone or small by the time children are school age. Much is still not known about what factors may exist to aid children who were exposed to cocaine "in utero". It is unknown if the effects of PCE are increased once children reach adolescence, or whether the neural rewiring that occurs during this developmental period attenuates the effects. A review of 27 studies performed between 2006 and 2012 found that cognitive development was mildly to moderately affected in PCE adolescents, but it was not clear how important these effects were in practical terms.

Unlike fetal alcohol syndrome, no set of characteristics has been discovered that results uniquely from cocaine exposure "in utero". Cocaine exposure "in utero" may affect the structure and function of the brain, predisposing children to developmental problems later, or these effects may be explained by children of crack-using mothers being at higher risk for domestic violence, deadbeat parenting, and maternal depression. When researchers are able to identify effects of PCE, these effects are typically small.

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.

There is a lack of good evidence to support the use of any particular intervention for morning sickness.

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.

Thalidomide was originally developed and prescribed as a cure for morning sickness in West Germany, but its use was discontinued when it was found to cause birth defects. The United States Food and Drug Administration never approved thalidomide for use as a cure for morning sickness.

Clear cells are rich in glycogen, which accounts for their histology.

After age 30 it was thought DES Daughters no longer were at risk for the disease, but as they age into their 40s and 50, cases continue to be reported. Researchers are now watching for a possible spike of CCA cases in post-menopausal DES Daughters, since this is when this cancer is normally diagnosed.

According to the Centers for Disease Control and Prevention (CDC), DES Daughters should have a special pap/pelvic exam every year because of their lifelong risk for clear-cell adenocarcinoma. The screening is similar to a routine exam but is more comprehensive and should be done every year for DES Daughters even after a hysterectomy. Although the cervix was removed in surgery, the vagina remains, and should be examined for the possible development of CCA. Updated screening guidelines in 2012 allow some women to skip annual Paps. But in developing the guidelines, the United States Preventative Services Task Force (USPSTF) specifically spelled out that the guidelines do NOT apply to DES Daughters, who should continue having annual screenings.

The susceptibility to risk of infection and immune deficiencies are active areas of research. Studies regarding the role of viruses in neonatal infections are lacking. Research also continues into the role and protective effect of gut, skin and other human microbiomes and the colonization during the neonatal period. The comparison between resource rich countries and resource poor countries makes it somewhat difficult to compare the diagnosis success since industrialized regions are able to confirm the diagnosis and presence of pathogens in the clinical laboratory. Clinical testing may not be available in all settings and clinicians must rely on the signs of infection in the newborn. Research data from Africa and Southeast Asia is scarce.

The result of some research has been the identification of diagnostic tools and procedures that could identify mothers with group B streptococcus infection in resource-poor regions. These procedures would be easy and inexpensive to use. Those mothers who are identified as being infected could then be prophylactly treated prior to the birth of the baby.

Probiotic administration of Lactobacillus species has shown some success.

A GBS vaccine is currently being tested but not currently available. Vaccination is estimated to being able to prevent 4% of GBS infections for preterm births and 60–70% for neonatal GBS infections in the US. The projected benefits of maternal vaccination is the prevention of 899 cases of GBS disease and 35 deaths among infants. The cost savings in the prevention of GBS may be over 43 million dollars. Vaccination may be especially beneficial in low to middle income countries where screening and prophylactic treatment is not possible. Analysts project that GBS vaccination would prevent 30–54% of infant GBS cases. Screening, prophylactic antibiotics and vaccine would prevent 48% of infection.

If HG is inadequately treated, anemia, hyponatremia, Wernicke's encephalopathy, kidney failure, central pontine myelinolysis, coagulopathy, atrophy, Mallory-Weiss tears, hypoglycemia, jaundice, malnutrition, pneumomediastinum, rhabdomyolysis, deconditioning, deep vein thrombosis, pulmonary embolism, splenic avulsion, or vasospasms of cerebral arteries are possible consequences. Depression and PTSD are common secondary complications of HG and emotional support can be beneficial.

Early onset sepsis can occur in the first week of life. It usually is apparent on the first day after birth. This type of infection is usually acquired before the birth of the infant. Premature rupture of membranes and other obstetrical complications can add to the risk of early-onset sepsis. If the amniotic membrane has been ruptured greater than 18 hours before delivery the infant may be at more risk for this complication. Prematurity, low birth weight, chorioamnionitis, maternal urinary tract infection and/or maternal fever are complications that increase the risk for early-onset sepsis. Early onset sepsis is indicated by serious respiratory symptoms. The infant usually suffers from pneumonia, hypothermia, or shock. The mortality rate is 30 to 50%.

While there is no cure for haemophilia, treatment improves outcomes.

The effects of HG on the fetus are mainly due to electrolyte imbalances caused by HG in the mother. Infants of women with severe hyperemesis who gain less than 7 kg (15.4 lb) during pregnancy tend to be of lower birth weight, small for gestational age, and born before 37 weeks gestation. In contrast, infants of women with hyperemesis who have a pregnancy weight gain of more than 7 kg appear similar to infants from uncomplicated pregnancies. There is no significant difference in the neonatal death rate in infants born to mothers with HG compared to infants born to mothers who do not have HG. Children born to mothers with undertreated Hyperemesis have a fourfold increase in neurobehavioral diagnoses.