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.

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.

Hyperemesis gravidarum is the presence of severe and persistent vomiting, causing dehydration and weight loss. It is more severe than the more common morning sickness and is estimated to affect 0.5–2.0% of pregnant women.

Gestational diabetes is when a woman without diabetes develops high blood sugar levels during pregnancy.

Associated terms for pregnancy are "gravid" and "parous". "Gravidus" and "gravid" come from the Latin for "heavy" and a pregnant female is sometimes referred to as a "gravida". Gravidity is a term used to describe the number of times that a female has been pregnant. Similarly, the term "parity" is used for the number of times that a female carries a pregnancy to a viable stage. Twins and other multiple births are counted as one pregnancy and birth. A woman who has never been pregnant is referred to as a "nulligravida." A woman who is (or has been only) pregnant for the first time is referred to as a "primigravida", and a woman in subsequent pregnancies as a "multigravida" or as "multiparous." Therefore, during a second pregnancy a woman would be described as "gravida 2, para 1" and upon live delivery as "gravida 2, para 2." In-progress pregnancies, abortions, miscarriages and/ or stillbirths account for parity values being less than the gravida number. In the case of a multiple birth the gravida number and parity value are increased by one only. Women who have never carried a pregnancy achieving more than 20 weeks of gestation age are referred to as "nulliparous."

The terms "preterm" and "postterm" have largely replaced earlier terms of "premature" and "postmature." "Preterm" and "postterm" are defined above, whereas "premature" and "postmature" have historical meaning and relate more to the infant's size and state of development rather than to the stage of pregnancy.

Miscarriage may occur for many reasons, not all of which can be identified. Risk factors are those things that increase the likelihood of having a miscarriage but don't necessarily cause a miscarriage. Up to 70 conditions, infections, medical procedures, lifestyle factors, occupational exposures, chemical exposure, and shift work are associated with increased risk for miscarriage. Some of these risks include endocrine, genetic, uterine, or hormonal abnormalities, reproductive tract infections, and tissue rejection caused by an autoimmune disorder.

There are various causes for recurrent miscarriage, and some can be treated. Some couples never have a cause identified, often after extensive investigations. About 50-75% of cases of Recurrent Miscarriage are unexplained.

Fifteen percent of women who have experienced three or more recurring miscarriages have some anatomical reason for the inability to complete the pregnancy. The structure of the uterus has an effect on the ability to carry a child to term. Anatomical differences are common and can be congenital.

In ICD-10, early pregnancy bleeding (code O20.9) refers to obstetrical hemorrhage before 20 completed weeks of gestational age.

First trimester bleeding, is obstetrical hemorrhage in the first trimester (0 weeks-12 weeks of gestational age). First trimester bleeding is a common occurrence and estimated to occur in approximately 25% of all (clinically recognized) pregnancies.

Differential diagnosis of first trimester bleeding is as follows, with the mnemonic AGE IS Low (during first trimester):

- Abortion (spontaneous), also referred to as miscarriage. One study came to the result that the risk of miscarriage during the course of the pregnancy with just spotting during the first trimester was 9%, and with light bleeding 12%, compared to 12% in pregnancies without any first trimester bleeding. However, heavy first trimester bleeding was estimated to have a miscarriage risk of 24%.

- Gestational trophoblastic neoplasia

- Ectopic pregnancy, which implies a pregnancy outside the uterus, commonly in the fallopian tube, which may lead to bleeding internally that could be fatal if untreated. In cases where there is heavy bleeding and an obstetric ultrasonography assists in diagnosing a pregnancy of unknown location (no visible intrauterine pregnancy), it has been estimated that approximately 6% have an underlying ectopic pregnancy.

- Implantation bleeding

- Chorionic hematoma

- Spotting

- Lower GU tract causes

- Vaginal bleed

- Cervical bleed

Other causes of early pregnancy bleeding may include:

- Postcoital bleeding, which is vaginal bleeding after sexual intercourse that can be normal with pregnancy

- Iatrogenic causes, or bleeding due to medical treatment or intervention, such as sex steroids, anticoagulants, or intrauterine contraceptive devices

- Infection

Obstetrical bleeding also known as obstetrical hemorrhage and maternal hemorrhage, refers to heavy bleeding during pregnancy, labor, or the postpartum period. Bleeding may be vaginal or less commonly but more dangerously, internal, into the abdominal cavity. Typically bleeding is related to the pregnancy itself, but some forms of bleeding are caused by other events.

The most frequent cause of maternal mortality worldwide is severe hemorrhage with 8.7 million cases occurring in 2015 and 83,000 of those events resulting in maternal death. Between 2003 and 2009, hemorrhage accounted for 27.1% of all maternal deaths globally

A Cervical pregnancy is an ectopic pregnancy that has implanted in the uterine endocervix. Such a pregnancy typically aborts within the first trimester, however, if it is implanted closer to the uterine cavity - a so-called cervico-isthmic pregnancy - it may continue longer. Placental removal in a cervical pregnancy may result in major hemorrhage.

The diagnosis is made in asymptomatic pregnant women either by inspection seeing a bluish discolored cervix or, more commonly, by obstetric ultrasonography. A typical non-specific symptom is vaginal bleeding during pregnancy. Ultrasound will show the location of the gestational sac in the cervix, while the uterine cavity is "empty". Cervical pregnancy can be confused with a miscarriage when pregnancy tissue is passing through the cervix.

Histologically the diagnosis has been made by Rubin’s criteria on the surgical specimen: cervical glands are opposite the trophoblastic tissue, the trophoblastic attachment is below the entrance of the uterine vessels to the uterus or the anterior peritoneal reflection, and fetal elements are absent from the uterine corpus. As many pregnancies today are diagnosed early and no hysterectomy is performed, Rubin's criteria can often not be applied.

Pregnancy over age 50 has, over recent years, become more possible for women, due to recent advances in assisted reproductive technology, in particular egg donation. Typically, a woman's fecundity ends with menopause, which by definition is 12 consecutive months without having had any menstrual flow at all. During perimenopause, the menstrual cycle and the periods become irregular and eventually stop altogether, but even when periods are still regular, the egg quality of women in their forties is lower than in younger women, making the likelihood of conceiving a healthy baby also reduced, particularly after age 42. It is important to note, that the female biological clock can vary greatly from woman to woman. A woman's individual level of fertility can be tested through a variety of methods.

Men also experience a decline in fertility as they age, for example, the average time to pregnancy if a man is under 25 is just over 4.5 months but nearly two years if a man is over 40 (if the woman is under 25). The risk of genetic defects is greatly increased due to the paternal age effect. Children with fathers aged 40 or older are more than five times as likely to have an autism spectrum disorder than children fathered by men aged under 30. Researchers estimate that compared to a male fathering a child in his early 20's - there is double the chance of the child getting schizophrenia when the father is age 40, and triple the risk of schizophrenia when the father is age 50 (though, for most people this means the risk goes from approximately 1 in 121 when a man is 29, to 1 in 47 when a man is age 50 to 54). Men's fertility declines throughout the lifespan, with the volume of a man’s semen and sperm motility (the ability of sperm to move towards an egg) decrease continually between the ages of 20 and 80. The risk of dwarfism and miscarriage also increases as men age

In the United States, between 1997 and 1999, 539 births were reported among mothers over age 50 (four per 100,000 births), with 194 being over 55.

The oldest mother to date to conceive, was 71 years, and the youngest mother, 5 years old. According to statistics from the Human Fertilisation and Embryology Authority, in the UK more than 20 babies are born to women over age 50 per year through in-vitro fertilization with the use of donor oocytes (eggs).

Maria del Carmen Bousada de Lara is the oldest verified mother; she was aged 66 years 358 days when she gave birth to twins; she was 130 days older than Adriana Iliescu, who gave birth in 2005 to a baby girl. In both cases the children were conceived through IVF with donor eggs. The oldest verified mother to conceive naturally (listed currently in the Guinness Records) is Dawn Brooke (UK); she conceived a son at the age of 59 years in 1997 while taking oestrogen.

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.

An intercurrent (or concurrent, concomitant or, in most cases, pre-existing) disease in pregnancy is a disease that is not directly caused by the pregnancy (in contrast to a complication of pregnancy), but which may become worse or be a potential risk to the pregnancy (such as "causing" pregnancy complications). A major component of this risk can result from necessary use of drugs in pregnancy to manage the disease.

In such circumstances, women who wish to continue with a pregnancy require extra medical care, often from an interdisciplinary team. Such a team might include (besides an obstetrician) a specialist in the disorder and other practitioners (for example, maternal-fetal specialists or obstetric physicians, dieticians, etc.).

Placenta accreta occurs when all or part of the placenta attaches abnormally to the myometrium (the muscular layer of the uterine wall). Three grades of abnormal placental attachment are defined according to the depth of attachment and invasion into the muscular layers of the uterus:

- Accreta – chorionic villi attach to the myometrium, rather than being restricted within the decidua basalis.

- Increta – chorionic villi invade into the myometrium.

- Percreta – chorionic villi invade through the perimetrium (uterine serosa).

Because of abnormal attachment to the myometrium, placenta accreta is associated with an increased risk of heavy bleeding at the time of attempted vaginal delivery. The need for transfusion of blood products is frequent, and hysterectomy is sometimes required to control life-threatening hemorrhage.

When the antepartum diagnosis of placenta accreta is made, it is usually based on ultrasound findings in the second or third trimester. Sonographic findings that may be suggestive of placenta accreta include:

1. Loss of normal hypoechoic retroplacental zone

2. Multiple vascular lacunae (irregular vascular spaces) within placenta, giving "Swiss cheese" appearance

3. Blood vessels or placental tissue bridging uterine-placental margin, myometrial-bladder interface, or crossing the uterine serosa

4. Retroplacental myometrial thickness of <1 mm

5. Numerous coherent vessels visualized with 3-dimensional power Doppler in basal view

Although there are isolated case reports of placenta accreta being diagnosed in the first trimester or at the time of abortion <20 weeks' gestational age, the predictive value of first-trimester ultrasound for this diagnosis remains unknown. Women with a placenta previa or "low-lying placenta" overlying a uterine scar early in pregnancy should undergo follow-up imaging in the third trimester with attention to the potential presence of placenta accreta.

Bleeding before the expected time of menarche could be a sign of precocious puberty. Other possible causes include the presence of a foreign body in the vagina, molestation, vaginal infection (vaginitis), and rarely, a tumor.

In pregnancy, there is an increased susceptibility and/or severity of several infectious diseases.

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.

Circumvallate placenta is a placental morphological abnormalitiy, a subtype of placenta extrachorialis in which the fetal membranes (chorion and amnion) "double back" on the fetal side around the edge of the placenta. After delivery, a circumvallate placenta has a thick ring of membranes on its fetal surface.

The fetal surface is divided into a central depressed zone surrounded by a thickened white ring which is incomplete the ring is situated at varying distance from the margin of the placenta. The ring is composed of a double fold of amnion and chorion with degenerated decidua vera and fibrin in between. Vessels radiate from the cord insertion as far as the ring and then disappear from the view.

Complete circumvallate placenta occurs in approximately 1% of pregnancies. It is diagnosed prenatally by medical ultrasonography, although one 1997 study of prenatal ultrasounds found that "of the normal placentas, 35% were graded as probably or definitely circumvallate by at least one sonologist," and "all sonologists misgraded the case of complete circumvallation as normal." The condition is associated with perinatal complications such as placental abruption, oligohydramnios, abnormal cardiotocography, preterm birth, and miscarriage.

Most unusual bleeding or irregular bleeding (metrorrhagia) in premenopausal women is caused by changes in the hormonal balance of the body. These changes are not pathological. Exceptionally heavy bleeding during menstruation is termed "menorrhagia" or "hypermenorrhea", while light bleeding is called "hypomenorrhea". Women on hormonal contraceptives can experience breakthrough bleeding and/or withdrawal bleeding. Withdrawal bleeding occurs when a hormonal contraceptive or other hormonal intake is discontinued.

There are pathological causes of unusual vaginal bleeding as well. Dysfunctional uterine bleeding is a common cause of menorrhagia and irregular bleeding. It is due to a hormonal imbalance, and symptoms can be managed by use of hormonal contraception (although hormonal contraception does not treat the underlying cause of the imbalance). If it is due to polycystic ovary syndrome, weight loss may help, and infertility may respond to clomifene citrate. Uterine fibroids (leiomyoma) are benign tumors of the uterus that cause bleeding and pelvic pain in approximately 30% of affected women. Adenomyosis, a condition in which the endometrial glands grow into the uterine muscle, can cause dysmenorrhea and menorrhagia. Cervical cancer may occur at premenopausal age, and often presents with "contact bleeding" (e.g. after sexual intercourse). Uterine cancer leads to irregular and often prolonged bleeding. In recently pregnant women who have delivered or who have had a miscarriage, vaginal bleeding may be a sign of endometritis or retained products of conception.

Diabetes mellitus and pregnancy deals with the interactions of diabetes mellitus (not restricted to gestational diabetes) and pregnancy. Risks for the child include miscarriage, growth restriction, growth acceleration, fetal obesity (macrosomia), polyhydramnios and birth defects.

Chorionic hematoma (also chorionic hemorrhage) is the pooling of blood (hematoma) between the chorion, a membrane surrounding the embryo, and the uterine wall. It occurs in about 3.1% of all pregnancies, it is the most common sonographic abnormality and the most common cause of first trimester bleeding.

A specific association of uterus didelphys (double uterus), unilateral hematocolpos (inadequate draining of menstrual blood) and ipsilateral renal agenesis (having only one kidney) has been described.