Signs of a miscarriage include vaginal spotting, abdominal pain or cramping, and fluid or tissue passing from the vagina. Bleeding can be a symptom of miscarriage, but many women also have bleeding in early pregnancy and don't miscarry. Bleeding during pregnancy may be referred to as a threatened miscarriage. Of those who seek clinical treatment for bleeding during pregnancy, about half will miscarry. Miscarriage may be detected during an ultrasound exam, or through serial human chorionic gonadotropin (HCG) testing.

The symptoms and discomforts of pregnancy are those presentations and conditions that result from pregnancy but do not significantly interfere with activities of daily living or pose a threat to the health of the mother or baby. This is in contrast to pregnancy complications. Sometimes a symptom that is considered a discomfort can be considered a complication when it is more severe. For example, nausea (morning sickness) can be a discomfort, but if, in combination with significant vomiting it causes a water-electrolyte imbalance, it is a complication known as hyperemesis gravidarum.

Common symptoms and discomforts of pregnancy include:

- Tiredness.

- Constipation

- Pelvic girdle pain

- Back pain

- Braxton Hicks contractions. Occasional, irregular, and often painless contractions that occur several times per day.

- Edema (swelling). Common complaint in advancing pregnancy. Caused by compression of the inferior vena cava and pelvic veins by the uterus leads to increased hydrostatic pressure in lower extremities.

- Increased urinary frequency. A common complaint, caused by increased intravascular volume, elevated glomerular filtration rate, and compression of the bladder by the expanding uterus.

- Urinary tract infection

- Varicose veins. Common complaint caused by relaxation of the venous smooth muscle and increased intravascular pressure.

- Haemorrhoids (piles). Swollen veins at or inside the anal area. Caused by impaired venous return, straining associated with constipation, or increased intra-abdominal pressure in later pregnancy.

- Regurgitation, heartburn, and nausea.

- Stretch marks

- Breast tenderness is common during the first trimester, and is more common in women who are pregnant at a young age.

In addition, pregnancy may result in pregnancy complication such as deep vein thrombosis or worsening of an intercurrent disease in pregnancy.

Miscarriage, also known as spontaneous abortion and pregnancy loss, is the natural death of an embryo or fetus before it is able to survive independently. Some use the cutoff of 20 weeks of gestation, after which fetal death is known as a stillbirth. The most common symptom of a miscarriage is vaginal bleeding with or without pain. Sadness, anxiety and guilt often occur afterwards. Tissue and clot-like material may leave the uterus and pass through and out of the vagina. When a woman keeps having miscarriages, infertility is present.

Risk factors for miscarriage include an older parent, previous miscarriage, exposure to tobacco smoke, obesity, diabetes, thyroid problems, and drug or alcohol use. About 80% of miscarriages occur in the first 12 weeks of pregnancy (the first trimester). The underlying cause in about half of cases involves chromosomal abnormalities. Diagnosis of a miscarriage may involve checking to see if the cervix is open or closed, testing blood levels of human chorionic gonadotropin (hCG), and an ultrasound. Other conditions that can produce similar symptoms include an ectopic pregnancy and implantation bleeding.

Prevention is occasionally possible with good prenatal care. Avoiding drugs, alcohol, infectious diseases, and radiation may prevent miscarriage. No specific treatment is usually needed during the first 7 to 14 days. Most miscarriages will complete without additional interventions. Occasionally the medication misoprostol or a procedure such as vacuum aspiration is used to remove the remaining tissue. Women who have a blood type of rhesus negative (Rh negative) may require Rho(D) immune globulin. Pain medication may be beneficial. Emotional support may help with negative emotions.

Miscarriage is the most common complication of early pregnancy. Among women who know they are pregnant, the miscarriage rate is roughly 10% to 20%, while rates among all fertilisation is around 30% to 50%. In those under the age of 35 the risk is about 10% while it is about 45% in those over the age of 40. Risk begins to increase around the age of 30. About 5% of women have two miscarriages in a row. Some recommend not using the term "abortion" in discussions with those experiencing a miscarriage in an effort to decrease distress.

Pregnancy, also known as gestation, is the time during which one or more offspring develops inside a woman. A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy can occur by sexual intercourse or assisted reproductive technology. Childbirth typically occurs around 40 weeks from the last menstrual period (LMP). This is just over nine months, where each month averages 29½ days. When measured from conception it is about 38 weeks. An embryo is the developing offspring during the first eight weeks following conception, after which, the term "fetus" is used until birth. Symptoms of early pregnancy may include missed periods, tender breasts, nausea and vomiting, hunger, and frequent urination. Pregnancy may be confirmed with a pregnancy test.

Pregnancy is typically divided into three trimesters. The first trimester is from week one through 12 and includes conception. Conception is when the sperm fertilizes the egg. The fertilized egg then travels down the fallopian tube and attaches to the inside of the uterus, where it begins to form the embryo and placenta. The first trimester carries the highest risk of miscarriage (natural death of embryo or fetus). The second trimester is from week 13 through 28. Around the middle of the second trimester, movement of the fetus may be felt. At 28 weeks, more than 90% of babies can survive outside of the uterus if provided with high-quality medical care. The third trimester is from 29 weeks through 40 weeks.

Prenatal care improves pregnancy outcomes. Prenatal care may include taking extra folic acid, avoiding drugs and alcohol, regular exercise, blood tests, and regular physical examinations. Complications of pregnancy may include disorders of high blood pressure, gestational diabetes, iron-deficiency anemia, and severe nausea and vomiting among others. Term pregnancy is 37 to 41 weeks, with early term being 37 and 38 weeks, full term 39 and 40 weeks, and late term 41 weeks. After 41 weeks, it is known as post term. Babies born before 37 weeks are preterm and are at higher risk of health problems such as cerebral palsy. Delivery before 39 weeks by labor induction or caesarean section is not recommended unless required for other medical reasons.

About 213 million pregnancies occurred in 2012, of which, 190 million were in the developing world and 23 million were in the developed world. The number of pregnancies in women ages 15 to 44 is 133 per 1,000 women. About 10% to 15% of recognized pregnancies end in miscarriage. In 2013, complications of pregnancy resulted in 293,000 deaths, down from 377,000 deaths in 1990. Common causes include maternal bleeding, complications of abortion, high blood pressure of pregnancy, maternal sepsis, and obstructed labor. Globally, 40% of pregnancies are unplanned. Half of unplanned pregnancies are aborted. Among unintended pregnancies in the United States, 60% of the women used birth control to some extent during the month pregnancy occurred.

Preterm birth causes a range of problems.

The main categories of causes of preterm birth are preterm labor induction and spontaneous preterm labor. Signs and symptoms of preterm labor include four or more uterine contractions in one hour. In contrast to false labour, true labor is accompanied by cervical dilatation and effacement. Also, vaginal bleeding in the third trimester, heavy pressure in the pelvis, or abdominal or back pain could be indicators that a preterm birth is about to occur. A watery discharge from the vagina may indicate premature rupture of the membranes that surround the baby. While the rupture of the membranes may not be followed by labor, usually delivery is indicated as infection (chorioamnionitis) is a serious threat to both fetus and mother. In some cases, the cervix dilates prematurely without pain or perceived contractions, so that the mother may not have warning signs until very late in the birthing process.

A review into using uterine monitoring at home to detect contractions and possible preterm births in women at higher risk of having a preterm baby found that it did not reduce the number of preterm births. The research included in the review was poor quality but it showed that home monitoring may increase the number of unplanned antenatal visits and may reduce the number of babies admitted to special care when compared with women receiving normal antenatal care.

Preterm infants usually show physical signs of prematurity in reverse proportion to the gestational age. As a result, they are at risk for numerous medical problems affecting different organ systems.

- Neurological problems include apnea of prematurity, hypoxic-ischemic encephalopathy (HIE), retinopathy of prematurity (ROP), developmental disability, transient hyperammonemia of the newborn, cerebral palsy and intraventricular hemorrhage, the latter affecting 25 percent of babies born preterm, usually before 32 weeks of pregnancy. Mild brain bleeds usually leave no or few lasting complications, but severe bleeds often result in brain damage or even death. Neurodevelopmental problems have been linked to lack of maternal thyroid hormones, at a time when their own thyroid is unable to meet postnatal needs.

- Cardiovascular complications may arise from the failure of the ductus arteriosus to close after birth: patent ductus arteriosus (PDA).

- Respiratory problems are common, specifically the respiratory distress syndrome (RDS or IRDS) (previously called hyaline membrane disease). Another problem can be chronic lung disease (previously called bronchopulmonary dysplasia or BPD).

- Gastrointestinal and metabolic issues can arise from neonatal hypoglycemia, feeding difficulties, rickets of prematurity, hypocalcemia, inguinal hernia, and necrotizing enterocolitis (NEC).

- Hematologic complications include anemia of prematurity, thrombocytopenia, and hyperbilirubinemia (jaundice) that can lead to kernicterus.

- Infection, including sepsis, pneumonia, and urinary tract infection

A study of 241 children born between 22 and 25 weeks who were currently of school age found that 46 percent had severe or moderate disabilities such as cerebral palsy, vision or hearing loss and learning problems. 34 percent were mildly disabled and 20 percent had no disabilities, while 12 percent had disabling cerebral palsy.

Drug use during pregnancy can have temporary or permanent effects on the fetus. Any drug that acts during embryonic or fetal development to produce a permanent alteration of form or function is known as a teratogen. Drugs may refer to both pharmaceutical drug and recreational drugs.

Twin-to-twin transfusion syndrome (TTTS), also known as feto-fetal transfusion syndrome (FFTS) and twin oligohydramnios-polyhydramnios sequence (TOPS) is a complication of disproportionate blood supply, resulting in high morbidity and mortality. It can affect monochorionic multiples, that is, multiple pregnancies where two or more fetuses share a chorion and hence a single placenta. Severe TTTS has a 60–100% mortality rate.

A staging system proposed by fetal surgeon Dr. Ruben Quintero is commonly used to classify the severity of TTTS.

Stage I: A small amount of amniotic fluid (oligohydramnios) is found around the donor twin and a large amount of amniotic fluid (polyhydramnios) is found around the recipient twin.

Stage II: In addition to the description above, the ultrasound is not able to identify the bladder in the donor twin.

Stage III: In addition to the characteristics of Stages I and II, there is abnormal blood flow in the umbilical cords of the twins.

Stage IV: In addition to all of the above findings, the recipient twin has swelling under the skin and appears to be experiencing heart failure (fetal hydrops).

Stage V: In addition to all of the above findings, one of the twins has died. This can happen to either twin. The risk to either the donor or the recipient is roughly equal & is quite high in Stage II or higher TTTS.

The Quintero staging does not provide information about prognosis, and other staging systems have been proposed.

Abortion is the ending of pregnancy by removing a fetus or embryo before it can survive outside the uterus. An abortion that occurs spontaneously is also known as a miscarriage. An abortion may be caused purposely and is then called an induced abortion, or less frequently, "induced miscarriage". The word "abortion" is often used to mean only induced abortions. A similar procedure after the fetus could potentially survive outside the womb is known as a "late termination of pregnancy".

When allowed by law, abortion in the developed world is one of the safest procedures in medicine. Modern methods use medication or surgery for abortions. The drug mifepristone in combination with prostaglandin appears to be as safe and effective as surgery during the first and second trimester of pregnancy. Birth control, such as the pill or intrauterine devices, can be used immediately following abortion. When performed legally and safely, induced abortions do not increase the risk of long-term mental or physical problems. In contrast, unsafe abortions (those performed by unskilled individuals, with hazardous equipment, or in unsanitary facilities) cause 47,000 deaths and 5 million hospital admissions each year. The World Health Organization recommends safe and legal abortions be available to all women.

Around 56 million abortions are performed each year in the world, with about 45% done unsafely. Abortion rates changed little between 2003 and 2008, before which they decreased for at least two decades as access to family planning and birth control increased. , 40% of the world's women had access to legal abortions without limits as to reason. Countries that permit abortions have different limits on how late in pregnancy abortion is allowed.

Historically, abortions have been done using herbal medicines, sharp tools, with force, or through other traditional methods. Abortion laws and cultural or religious views of abortions are different around the world. In some areas abortion is legal only in specific cases such as rape, problems with the fetus, poverty, risk to a woman's health, or incest. In many places there is much debate over the moral, ethical, and legal issues of abortion. Those who oppose abortion often maintain that an embryo or fetus is a human with a right to life and may compare abortion to murder. Those who favor the legality of abortion often hold that a woman has a right to make decisions about her own body.

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.

Rh disease (also known as rhesus isoimmunisation, Rh (D) disease, rhesus incompatibility, rhesus disease, RhD hemolytic disease of the newborn, rhesus D hemolytic disease of the newborn or RhD HDN) is a type of hemolytic disease of the newborn (HDN). The disease ranges from mild to severe, and typically occurs only in some second or subsequent pregnancies of Rh negative women where the fetus's father is Rh positive, leading to a Rh+ pregnancy. During birth, the mother may be exposed to the infant's blood, and this causes the development of antibodies, which may affect the health of subsequent Rh+ pregnancies. In mild cases, the fetus may have mild anaemia with reticulocytosis. In moderate or severe cases the fetus may have a more marked anaemia and erythroblastosis fetalis (hemolytic disease of the newborn). When the disease is very severe it may cause hydrops fetalis or stillbirth.

Rh disease is generally preventable by treating the mother during pregnancy or soon after delivery with an intramuscular injection of anti-RhD immunoglobulin (Rho(D) immune globulin). The RhD protein is coded by the RHD gene.

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.

Abortion doping refers to the rumoured practice of purposely inducing pregnancy for athletic performance-enhancing benefits, then aborting the pregnancy.

Spontaneous abortion, also known as miscarriage, is the unintentional expulsion of an embryo or fetus before the 24th week of gestation. A pregnancy that ends before 37 weeks of gestation resulting in a live-born infant is known as a "premature birth" or a "preterm birth". When a fetus dies in utero after viability, or during delivery, it is usually termed "stillborn". Premature births and stillbirths are generally not considered to be miscarriages although usage of these terms can sometimes overlap.

Only 30% to 50% of conceptions progress past the first trimester. The vast majority of those that do not progress are lost before the woman is aware of the conception, and many pregnancies are lost before medical practitioners can detect an embryo. Between 15% and 30% of known pregnancies end in clinically apparent miscarriage, depending upon the age and health of the pregnant woman. 80% of these spontaneous abortions happen in the first trimester.

The most common cause of spontaneous abortion during the first trimester is chromosomal abnormalities of the embryo or fetus, accounting for at least 50% of sampled early pregnancy losses. Other causes include vascular disease (such as lupus), diabetes, other hormonal problems, infection, and abnormalities of the uterus. Advancing maternal age and a woman's history of previous spontaneous abortions are the two leading factors associated with a greater risk of spontaneous abortion. A spontaneous abortion can also be caused by accidental trauma; intentional trauma or stress to cause miscarriage is considered induced abortion or feticide.

Autoimmune disease in women is a description of the autoimmune diseases that effect women. Some of these differences are unique to women such as the effects during pregnancy. Women with autoimmune diseases can safely have children. There are be some risks for the mother or baby, depending on the disease and how severe it is. For instance, pregnant women with lupus have a higher risk of preterm birth and stillbirth. Pregnant women with myasthenia gravis (MG) might have symptoms that lead to trouble breathing during pregnancy. For some women, symptoms tend to improve during pregnancy, while others find their symptoms tend to flare up. Also, some medicines used to treat autoimmune diseases might not be safe to use during pregnancy.

For women with systemic lupus erythematosus (SLE), pregnancy can present some particular challenges for both mother and child.

While most infants born to mothers who have SLE are healthy, mothers with SLE as an intercurrent disease in pregnancy should remain under medical care until delivery. In general, women with SLE and, in addition, hypertension, proteinuria, and azotemia have an extra increased risk for pregnancy complications. Pregnancy outcomes in women with SLE who receive renal transplants are similar to those of transplant recipients without SLE.

Women pregnant and known to have anti-Ro (SSA) or anti-La antibodies (SSB) often have echocardiograms during the 16th and 30th weeks of pregnancy to monitor the health of the heart and surrounding vasculature.

Contraception and other reliable forms of pregnancy prevention is routinely advised for women with SLE, since getting pregnant during active disease was found to be harmful. Lupus nephritis was the most common manifestation.

Of live births, approximately one third are delivered prematurely.

Antenatal depression, also known as Prenatal depression, is a form of clinical depression that can affect a woman during pregnancy, and can be a precursor to postpartum depression if not properly treated. It is estimated that 7% to 20% percent of pregnant women are affected by this condition. Any form of prenatal stress felt by the mother can have negative effects on various aspects of fetal development, which can cause harm to the mother and child. Antenatal depression is often caused by the stress and worry that pregnancy can bring, only at a more severe level. Other risk factors include unplanned pregnancy, difficulty becoming pregnant, history of abuse, and economic or family situations.

Commonly, symptoms involve how the patient views herself, how she feels about going through such a life changing event, the restrictions on the mother's lifestyle that motherhood will place, or how the partner or family feel about the baby. Pregnancy places significant strain on a woman's body, so some stress, mood swings, sadness, irritability, pain, and memory changes are to be expected. Antenatal depression can be extremely dangerous for the health of the mother, and the baby, if not properly treated.

Aggravation (or exacerbation) of SLE has been estimated to occur in about 20-30% pregnancies where the mother has SLE. Increased disease activity of SLE is expected during pregnancy because of increased levels of estrogen, prolactin, and certain cytokines. However, a long time of remission before pregnancy decreases the risk of aggravation, with an incidence of 7-33% in women who have been in remission for at least 6 months, and an incidence of 61-67% in women who have active SLE at the time of conception.

Renal disease flare-up is the most common presentation of SLE aggravation in pregnancy, and is seen equally in United States and European populations. Serositis with pleural and pericardial effusions are seen in up to 10% of these patients.

On the other hand, flares of SLE are uncommon during pregnancy and are often easily treated. The most common symptoms of these flares include arthritis, rashes, and fatigue.

Also, in the postpartum period, there may be exacerbations of SLE due to decreased levels of anti-inflammatory steroids, elevated levels of prolactin and estrogen and progesterone changes.

In diagnosing an aggravation of SLE in pregnancy, there need to be a differential diagnosis from SLE-unrelated complications of pregnancy that may appear in a similar fashion. For example, chloasma may appear like the malar rash of SLE, proteinuria from preeclampsia may appear like that of lupus nephritis, thrombocytopenia of the HELLP syndrome may appear like that of SLE, and pregnancy-related edema of joints can appear like arthritis of SLE.

Hormonal and other changes in pregnancy affect physical performance. In the first three months it is known that a woman’s body produces a natural surplus of red blood cells, which are well supplied with oxygen-carrying hemoglobin, in order to support the growing fetus. A study of athletes before and after pregnancy by Professor James Pivarnik at the Human Energy Research laboratory in Michigan State University has found there is a 60 per cent increase in blood volume and that this could improve the body’s ability to carry oxygen to muscles by up to 30 percent. This would have obvious positive effects on aerobic capacity. Other potential advantages are obtained from the surge in hormones that pregnancy induces, predominantly progesterone and estrogen, but also testosterone, which could increase muscle strength. Increases in hormones like relaxin, which loosens the hip joints to prepare for childbirth, may have a performance-enhancing effect on joint mobility.

Several world records have been set by female athletes shortly after giving birth to their first child. This is accepted as a natural and unintended event.

Both are composed of intermediate trophoblast, but their morphological features and clinical presentation can differ significantly.

Exaggerated placental site is a benign, non cancerous lesion with an increased number of implantation site intermediate trophoblastic cells that infiltrate the endometrium and the underlying myometrium. An exaggerated placental site may occur with normal pregnancy, or after an abortion. No specific treatment or follow up is necessary.

Placental site nodules are lesions of chorionic type intermediate trophoblast, usually small. 40 to 50% of placental site nodules are found in the cervix. They almost always are incidental findings after a surgical procedure. No specific treatment or follow up is necessary.

Antenatal depression is classified based on a woman's symptoms. During pregnancy, a lot of changes to mood, memory, eating habits, and sleep is common. When these common traits become severe, and begin to alter one's day-to-day life, that is when it is considered to be antenatal depression. Symptoms of Antenatal depression are:

- Inability to concentrate.

- Difficulty remembering.

- Feeling emotionally numb.

- Extreme irritability.

- Sleeping too much or not enough, or restless sleep.

- Extreme or unending fatigue.

- Desire to over eat, or not eat at all.

- Weight loss/gain unrelated to pregnancy.

- Loss of interest in sex.

- A sense of dread about everything, including the pregnancy.

- Feelings of failure, or guilt.

- Persistent sadness.

- Thoughts of suicide, or death.

Other symptoms can include the inability to get excited about the pregnancy, and/or baby, a feeling of disconnection with the baby, and an inability to form/feel a bond with the developing baby. This can drastically affect the relationship between the mother and the baby, and can drastically affect the mother's capacity for self care. Such inadequacies can lead to even greater risk factors for the mother. Antenatal depression can be triggered by various causes, including relationship problems, family or personal history of depression, infertility, previous pregnancy loss, complications in pregnancy, and a history of abuse or trauma.

An interstitial pregnancy is a uterine but ectopic pregnancy; the pregnancy is located outside the uterine cavity in that part of the fallopian tube that penetrates the muscular layer of the uterus. The term cornual pregnancy is sometimes used as a synonym, but remains ambiguous as it is also applied to indicate the presence of a pregnancy located within the cavity in one of the two upper "horns" of a bicornuate uterus. Interstitial pregnancies have a higher mortality than ectopics in general.

Gestational trophoblastic disease (GTD) is a term used for a group of pregnancy-related tumours. These tumours are rare, and they appear when cells in the womb start to proliferate uncontrollably. The cells that form gestational trophoblastic tumours are called trophoblasts and come from tissue that grows to form the placenta during pregnancy.

There are several different types of GTD. Hydatidiform moles are benign in most cases, but sometimes may develop into invasive moles, or, in rare cases, into choriocarcinoma, which is likely to spread quickly, but which is very sensitive to chemotherapy, and has a very good prognosis. Gestational trophoblasts are of particular interest to cell biologists because, like cancer, these cells invade tissue (the uterus), but unlike cancer, they sometimes "know" when to stop.

GTD can simulate pregnancy, because the uterus may contain fetal tissue, albeit abnormal. This tissue may grow at the same rate as a normal pregnancy, and produces chorionic gonadotropin, a hormone which is measured to monitor fetal well-being.

While GTD overwhelmingly affects women of child-bearing age, it may rarely occur in postmenopausal women.

Though GBS colonization is asymptomatic and, in general, does not cause problems, it can sometimes cause serious illness for the mother and the baby during gestation and after delivery. GBS infections in the mother can cause chorioamnionitis (intra-amniotic infection or severe infection of the placental tissues) infrequently, and postpartum infections (after birth). GBS urinary tract infections may induce labour and cause premature delivery (preterm birth) and miscarriage.