Advanced maternal age, in a broad sense, is the instance of a woman being of an older age at a stage of reproduction, although there are various definitions of specific age and stage of reproduction. The variability in definitions is in part explained by the effects of increasing age occurring as a continuum rather than as a threshold effect.

In Western, Northern, and Southern Europe, first-time mothers are on average 26 to 29 years old, up from 23 to 25 years at the start of the 1970s. In a number of European countries (Spain), the mean age of women at first childbirth has crossed the 30 year threshold.

This process is not restricted to Europe. Asia, Japan and the United States are all seeing average age at first birth on the rise, and increasingly the process is spreading to countries in the developing world like China, Turkey and Iran. In the U.S., the average age of first childbirth was 26 in 2013.

Advanced maternal age is associated with adverse reproductive effects such as increased risk of infertility, and that the children have chromosomal abnormalities. The corresponding paternal age effect is less pronounced.

In present generations it is more common to have children at an older age. Several factors may influence the decisions of parents when having their first baby. Such factors include educational, social and economic status.

A woman's fertility peaks lasts during the twenties and first half of thirties, after which it starts to decline, with advanced maternal age causing an increased risk of female infertility.

According to Henri Leridon, PhD, an epidemiologist with the French Institute of Health and Medical Research, of women trying to get pregnant, without using fertility drugs or in vitro fertilization:

- At age 30

- 75% will have a conception ending in a live birth within one year

- 91% will have a conception ending in a live birth within four years.

- At age 35

- 66% will have a conception ending in a live birth within one year

- 84% will have a conception ending in a live birth within four years.

- At age 40

- 44% will have a conception ending in a live birth within one year

- 64% will have a conception ending in a live birth within four years.

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.

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.

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.

There are 2 major categories of IUGR: symmetrical and asymmetrical. Some conditions are associated with both symmetrical and asymmetrical growth restriction.

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

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.

Intrauterine growth restriction (IUGR) refers to poor growth of a fetus while in the mother's womb during pregnancy. The causes can be many, but most often involve poor maternal nutrition or lack of adequate oxygen supply to the fetus.

At least 60% of the 4 million neonatal deaths that occur worldwide every year are associated with low birth weight (LBW), caused by intrauterine growth restriction (IUGR), preterm delivery, and genetic/chromosomal abnormalities, demonstrating that under-nutrition is already a leading health problem at birth.

Intrauterine growth restriction can result in a baby being Small for Gestational Age (SGA), which is most commonly defined as a weight below the 10th percentile for the gestational age. At the end of pregnancy, it can result in a low birth weight.

Large for gestational age (LGA) is an indication of high prenatal growth rate.

LGA is often defined as a weight, length, or head circumference that lies above the 90th percentile for that gestational age. However, it has been suggested that the definition be restricted to infants with birth weights greater than the 97th percentile (2 standard deviations above the mean) as this more accurately describes infants who are at greatest risk for perinatal morbidity and mortality.

Macrosomia, which literally means "long body", is sometimes confused with LGA. Some experts consider a baby to be big when it weighs more than at birth, and others say a baby is big if it weighs more than . A baby is also called “large for gestational age” if its weight is greater than the 90th percentile at birth.

According to the World Health Organization, if a woman present any of the conditions below during pregnancy, childbirth or within 42 days of termination of pregnancy and survive, she is considered as a maternal near miss case.

Cardiovascular dysfunction

Respiratory dysfunction

Renal dysfunction

Coagulation dysfunction

Hepatic dysfunction

Neurologic dysfunction

Uterine dysfunction

Female fertility is affected by age. Age is thus a major fertility factor for women. Menarche, the first menstrual period, usually occurs around 12-13, although it may happen earlier or later, depending on each girl. After puberty, female fertility increases and then decreases, with advanced maternal age causing an increased risk of female infertility. In humans, a woman's fertility peaks in the early and mid-20s, after which it starts to decline slowly. While many sources suggest a more dramatic drop at around 35, this is unclear since studies are still cited from the nineteenth century and earlier. One 2004 study of European women found fertility of the 27-34 and the 35–39 groups had only a four-percent difference. At age 45, a woman starting to try to conceive will have no live birth in 50–80 percent of cases. Menopause, or the cessation of menstrual periods, generally occurs in the 40s and 50s and marks the cessation of fertility, although age-related infertility can occur before then. The relationship between age and female fertility is sometimes referred to as a woman's "biological clock."

LGA and macrosomia cannot be diagnosed until after birth, as it is impossible to accurately estimate the size and weight of a child in the womb. Babies that are large for gestational age throughout the pregnancy may be suspected because of an ultrasound, but fetal weight estimations in pregnancy are quite imprecise. For non-diabetic women, ultrasounds and care providers are equally inaccurate at predicting whether or not a baby will be big. If an ultrasound or a care provider predicts a big baby, they will be wrong half the time.

Although big babies are born to only 1 out of 10 women, the 2013 Listening to Mothers Survey found that 1 out of 3 American women were told that their babies were too big. In the end, the average birth weight of these suspected “big babies” was only . In the end, care provider concerns about a suspected big baby were the fourth-most common reason for an induction (16% of all inductions), and the fifth-most common reason for a C-section (9% of all C-sections). This treatment is not based on current best evidence.

Research has consistently shown that, as far as birth complications are concerned, the care provider’s perception that a baby is big is more harmful than an actual big baby by itself. In a 2008 study, researchers compared what happened to women who were suspected of having a big baby to what happened to women who were not suspected of having a big baby—but who ended up having one. In the end, women who were suspected of having a big baby (and actually had one) had a triple in the induction rate, more than triple the C-section rate, and a quadrupling of the maternal complication rate, compared to women who were not suspected of having a big baby but who had one anyway.

Complications were most often due to C-sections and included bleeding (hemorrhage), wound infection, wound separation, fever, and need for antibiotics. There were no differences in shoulder dystocia between the two groups. In other words, when a care provider “suspected” a big baby (as compared to not knowing the baby was going to be big), this tripled the C-section rates and made mothers more likely to experience complications, without improving the health of babies.

In the early stages of placental abruption, there may be no symptoms. When symptoms develop, they tend to develop suddenly. Common symptoms include sudden-onset abdominal pain, contractions that seem continuous and do not stop, vaginal bleeding, enlarged uterus disproportionate to the gestational age of the fetus, decreased fetal movement, and decreased fetal heart rate.

Vaginal bleeding, if it occurs, may be bright red or dark.

A placental abruption caused by arterial bleeding at the center of the placenta leads to sudden development of severe symptoms and life-threatening conditions including fetal heart rate abnormalities, severe maternal hemorrhage, and disseminated intravascular coagulation (DIC). Those abruptions caused by venous bleeding at the periphery of the placenta develop more slowly and cause small amounts of bleeding, intrauterine growth restriction, and oligohydramnios (low levels of amniotic fluid).

Low birth weight (LBW) is defined by the World Health Organization as a birth weight of a

infant of 2,499 g or less, regardless of gestational age. Subcategories include very low birth weight (VLBW), which is less than 1500 g (3 pounds 5 ounces), and extremely low birth weight (ELBW), which is less than 1000 g (2 pounds 3 ounces). Normal weight at term delivery is 2500–4200 g (5 pounds 8 ounces – 9 pounds 4 ounces).

Swelling (especially in the hands and face) was originally considered an important sign for a diagnosis of pre-eclampsia. However, because swelling is a common occurrence in pregnancy, its utility as a distinguishing factor in pre-eclampsia is not high. Pitting edema (unusual swelling, particularly of the hands, feet, or face, notable by leaving an indentation when pressed on) can be significant, and should be reported to a health care provider.

In general, none of the signs of pre-eclampsia are specific, and even convulsions in pregnancy are more likely to have causes other than eclampsia in modern practice. Further, a symptom such as epigastric pain may be misinterpreted as heartburn. Diagnosis, therefore, depends on finding a coincidence of several pre-eclamptic features, the final proof being their regression after delivery.

The World Health Organization defines a maternal near-miss case as "a woman who nearly died but survived a complication that occurred during pregnancy, childbirth or within 42 days of termination of pregnancy."

Like amniotic fluid, blood, semen, vaginal infections, antiseptics, basic urine, and cervical mucus also have a basic pH and can also turn nitrazine paper blue. Cervical mucus can also make a pattern similar to ferning on a microscope slide, but it is usually patchy and with less branching.

Other things to keep in mind that may present similarly to premature rupture of membranes are the following:

- Urinary incontinence: leakage of small amounts of urine is common in the last part of pregnancy

- Normal vaginal secretions of pregnancy

- Increased sweat or moisture around the perineum

- Increased cervical discharge: this can happen when there is a genital tract infection

- Semen

- Douching

- Vesicovaginal fistula: an abnormal connection between the bladder and the vagina

- Loss of the mucus plug

Women with a luteoma of pregnancy typically don't show any symptoms. Only 36% of women actually show signs of masculinization. These signs include acne, the growth of dark hair (especially on the face), deepening of the voice, temporal balding, and clitoromegaly. An increase in testosterone levels in the mother doesn't necessarily mean masculinization will occur. During a normal pregnancy, the testosterone level will increase slightly in the first and second trimester, but doubles in the third trimester. The testosterone level also depends on the sex of the fetus; male fetuses cause a bigger increase in testosterone levels than female fetuses.

HELLP syndrome is defined as hemolysis (microangiopathic), elevated liver enzymes (liver dysfunction), and low platelets (thrombocytopenia). This condition may occur in 10–20% of patients with severe pre-eclampsia and eclampsia and is associated with increased maternal and fetal morbidity and mortality. In 50% of instances, HELLP syndrome develops preterm, while 20% of cases develop in late gestation and 30% during the post-partum period.

In most cases Ballantyne syndrome causes fetal or neonatal death and in contrast, maternal involvement is limited at the most to preeclampsia.

Placental abruption is when the placenta separates early from the uterus, in other words separates before childbirth. It occurs most commonly around 25 weeks of pregnancy. Symptoms may include vaginal bleeding, lower abdominal pain, and dangerously low blood pressure. Complications for the mother can include disseminated intravascular coagulopathy and kidney failure. Complications for the baby can include fetal distress, low birthweight, preterm delivery, and stillbirth.

The cause of placental abruption is not entirely clear. Risk factors include smoking, preeclampsia, prior abruption, trauma during pregnancy, cocaine use, and previous cesarean section. Diagnosis is based on symptoms and supported by ultrasound. It is classified as a complication of pregnancy.

For small abruption bed rest may be recommended while for more significant abruptions or those that occur near term, delivery may be recommended. If everything is stable vaginal delivery may be tried, otherwise cesarean section is recommended. In those less than 36 weeks pregnant, corticosteroids may be given to speed development of the babies lungs. Treatment may require blood transfusion or emergency hysterectomy.

Placental abruption occurs in about 1 in 200 pregnancies. Along with placenta previa and uterine rupture it is one of the most common cause of vaginal bleeding in the later part of pregnancy. Placental abruption is the reason for about 15% of infant deaths around the time of birth. The condition was described at least as early as 1664.

Although many pregnant women with high blood pressure have healthy babies without serious problems, high blood pressure can be dangerous for both the mother and baby. Women with pre-existing, or chronic, high blood pressure are more likely to have certain complications during pregnancy than those with normal blood pressure. However, some women develop high blood pressure while they are pregnant (often called gestational hypertension).

Chronic poorly-controlled high blood pressure before and during pregnancy puts a pregnant woman and her baby at risk for problems. It is associated with an increased risk for maternal complications such as preeclampsia, placental abruption (when the placenta separates from the wall of the uterus), and gestational diabetes. These women also face a higher risk for poor birth outcomes such as preterm delivery, having an infant small for his/her gestational age, and infant death.