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

Asymmetrical IUGR is more common (70%). In asymmetrical IUGR, there is restriction of weight followed by length. The head continues to grow at normal or near-normal rates (head sparing). A lack of subcutaneous fat leads to a thin and small body out of proportion with the liver. Normally at birth the brain of the fetus is 3 times the weight of its liver. In IUGR, It becomes 5-6 times. In these cases, the embryo/fetus has grown normally for the first two trimesters but encounters difficulties in the third, sometimes secondary to complications such as pre-eclampsia. Other symptoms than the disproportion include dry, peeling skin and an overly-thin umbilical cord. The baby is at increased risk of hypoxia and hypoglycaemia. This type of IUGR is most commonly caused by extrinsic factors that affect the fetus at later gestational ages. Specific causes include:

- Chronic high blood pressure

- Severe malnutrition

- Genetic mutations, Ehlers–Danlos syndrome

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.

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).

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.

Small for gestational age (SGA) newborns are those who are smaller in size than normal for the gestational age, most commonly defined as a weight below the 10th percentile for the gestational age.

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

Being small for gestational age is broadly either:

- Being constitutionally small, wherein the state is basically a genetic trait of the baby.

- Intrauterine growth restriction, also called "pathological SGA"

Each year, ill health as a result of pregnancy is experienced (sometimes permanently) by more than 20 million women around the world. In 2013 complications of pregnancy resulted in 293,000 deaths down from 377,000 deaths in 1990. Common causes include maternal bleeding (44,000), complications of abortion (44,000), high blood pressure of pregnancy (29,000), maternal sepsis (24,000), and obstructed labor (19,000).

The following are some examples of pregnancy complications:

- Pregnancy induced hypertension

- Anemia

- Postpartum depression

- Postpartum psychosis

- Thromboembolic disorders. These are the leading cause of death in pregnant women in the US.

- PUPPP (Pruritic Urticarial Papules and Plaques of Pregnancy), a skin disease that develops around the 32nd week. Signs are red plaques, papules, and itchiness around the belly button that then spreads all over the body except for the inside of hands and face.

- Ectopic pregnancy, implantation of the embryo outside the uterus.

- Hyperemesis gravidarum, excessive nausea and vomiting that is more severe than normal morning sickness.

- Pulmonary embolism, blood clots that form in the legs that can migrate to the lungs.

There is also an increased susceptibility and severity of certain infections in pregnancy.

LBW is either caused by preterm birth (that is, a low gestational age at birth, commonly defined as younger than 37 weeks of gestation) or the infant being small for gestational age (that is, a slow prenatal growth rate), or a combination of both.

In general, risk factors in the mother that may contribute to low birth weight include young ages, multiple pregnancies, previous LBW infants, poor nutrition, heart disease or hypertension, untreated coeliac disease, drug addiction, alcohol abuse, and insufficient prenatal care. Environmental risk factors include smoking, lead exposure, and other types of air pollutions.

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 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).

Types of breech depend on how the baby’s legs are lying.

- A frank breech (otherwise known as an extended breech) is where the baby’s legs are up next to its abdomen, with its knees straight and its feet next to its ears. This is the most common type of breech.

- A complete breech (flexed) breech is when the baby appears as though it is sitting crossed-legged with its legs bent at the hips and knees.

- A footling breech is when one or both of the baby’s feet are born first instead of the pelvis. This is more common in babies born prematurely or before their due date.

In addition to the above, breech births in which the sacrum is the fetal denominator can be classified by the position of a fetus. Thus sacro-anterior, sacro-transverse and sacro-posterior positions all exist, but left sacro-anterior is the most common presentation. Sacro-anterior indicates an easier delivery compared to other forms.

The beginning of pregnancy may be detected either based on symptoms by the woman herself, or by using pregnancy tests. However, an important condition with serious health implications that is quite common is the denial of pregnancy by the pregnant woman. About one in 475 denials will last until around the 20th week of pregnancy. The proportion of cases of denial, persisting until delivery is about 1 in 2500. Conversely, some non-pregnant women have a very strong belief that they are pregnant along with some of the physical changes. This condition is known as a false pregnancy.

Fetal entities: First twin 17-30%; Second twin 28-39%; Stillborn 26%; Prader-Willi syndrome 50%, Werdnig-Hoffman syndrome 10%; Smith-Lemli-Opitz syndrome 40%; Fetal alcohol syndrome 40%; Potter anomaly 36%; Zellweger syndrome 27%; Myotonic dystrophy 21%, 13 trisomy syndrome 12%; 18 trisomy syndrome 43%; 21 trisomy syndrome 5%; de Lange syndrome 10%; Anencephalus 6-18%, Spina bifida 20-30%; Congenital Hydrocephalus 24-37%; Osteogenesis imperfecta 33.3%; Amyoplasia 33.3%; Achondrogenesis 33.3%; Amelia 50%; Craniosynostosis 8%; Sacral agenesis 30.4%; Arthrogriposis multiplex congenita 33.3; Congenital dislocation of the hip 33.3%; Hereditary sensory neuropathy type III 25%; Centronuclear myoptathy 16.7%; Multiple pituitary hormone deficiency 50%; Isolated pituitary hormone deficiency 20%; Ectopic posterior pituitary gland 33.3%; Congenital bilateral perisilvian syndrome 33.3; Symmetric fetal growth restriction 40%; Asymmetric fetal growth restriction 40%; Nonimmune hydrops fetalis 15%; Atresio ani 18.2%; Microcephalus 15.4%; Omphalocele 12.5%; Prematurity 40%

Placental and amniotic fluid entities: Amniotic sheet perpendicular to the placenta 50%; Cornual-fundal implantation of the placenta 30%; Placenta previa 12.5%; Oligohydramnios 17%; Polyhydramnios 15.8%; MATERNAL ENTITIES: Uterus arcuatus 22.6%; Uterus unicornuatus 33.3%; Uterus bicornuatus 34.8%; Uterus didelphys 30-41%; Uterus septus 45.8%; Leimyoma uteri 9-20%; Spinal cord injury 10%; Carriers of Duchenne muscular dystrophy 17%

Combination of two medical entities: First twin in uterus with two bodies 14.29%; Second twin in uterus with two bodies 18.52%.

Also, women with previous Caesarean deliveries have a risk of breech presentation at term twice that of women with previous vaginal deliveries.

The highest possible probability of breech presentation of 50% indicates that breech presentation is a consequence of random filling of the intrauterine space, with the same probability of breech and cephalic presentation in a longitudinally elongated uterus.

Based on severity:

- Class 0: Asymptomatic. Diagnosis is made retrospectively by finding an organized blood clot or a depressed area on a delivered placenta.

- Class 1: Mild and represents approximately 48% of all cases. Characteristics include the following:

- No vaginal bleeding to mild vaginal bleeding

- Slightly tender uterus

- Normal maternal blood pressure and heart rate

- No coagulopathy

- No fetal distress

- Class 2: Moderate and represents approximately 27% of all cases. Characteristics include the following:

- No vaginal bleeding to moderate vaginal bleeding

- Moderate-to-severe uterine tenderness with possible tetanic contractions

- Maternal tachycardia with orthostatic changes in blood pressure and heart rate

- Fetal distress

- Hypofibrinogenemia (i.e., 50–250 mg/dL)

- Class 3: Severe and represents approximately 24% of all cases. Characteristics include the following:

- No vaginal bleeding to heavy vaginal bleeding

- Very painful tetanic uterus

- Maternal shock

- Hypofibrinogenemia (i.e., <150 mg/dL)

- Coagulopathy

- Fetal death

No single diagnostic test currently exists to predict the likelihood of developing gestational hypertension. High blood pressure is the major sign in diagnosing gestational hypertension. Protein in the urine, proteinuria, is a key indicator of the condition. Some women with gestational hypertension may present asymptomatic, but a number of symptoms are associated with the condition.

Symptoms

- Edema

- Sudden weight gain

- Blurred vision or sensitivity to light

- Nausea and vomiting

- Persistent headaches

- Increased blood pressure

Women with placenta previa often present with painless, bright red vaginal bleeding. This commonly occurs around 32 weeks of gestation, but can be as early as late mid-trimester. 51.6% of women with placenta previa have antepartum haemorrhage. This bleeding often starts mildly and may increase as the area of placental separation increases. Previa should be suspected if there is bleeding after 24 weeks of gestation. Bleeding after delivery occurs in about 22% of those affected.

Women may also present as a case of failure of engagement of fetal head.

The common clinical features are smaller symphysis fundal height, fetal malpresentation, undue prominence of fetal parts and reduced amount of amniotic fluid.

Gestational hypertension or pregnancy-induced hypertension (PIH) is the development of new hypertension in a pregnant woman after 20 weeks gestation without the presence of protein in the urine or other signs of preeclampsia. Hypertension is defined as having a blood pressure

greater than 140/90 mm Hg.

Complications may include cord compression, musculoskeletal abnormalities such as facial distortion and clubfoot, pulmonary hypoplasia and intrauterine growth restriction. Amnion nodosum is frequently also present (nodules on the fetal surface of the amnion).

The use of oligohydramnios as a predictor of gestational complications is controversial.

Potter syndrome is a condition caused by oligohydramnios. Affected fetuses develop pulmonary hypoplasia, limb deformities, and characteristic facies. Bilateral agenesis of the fetal kidneys is the most common cause due to the lack of fetal urine.

Placenta praevia is when the placenta attaches inside the uterus but near or over the cervical opening. Symptoms include vaginal bleeding in the second half of pregnancy. The bleeding is bright red and tends not to be associated with pain. Complications may include placenta accreta, dangerously low blood pressure, or bleeding after delivery. Complications for the baby may include fetal growth restriction.

Risk factors include pregnancy at an older age and smoking as well as prior cesarean section, labor induction, or termination of pregnancy. Diagnosis is by ultrasound. It is classified as a complication of pregnancy.

For those who are less than 36 weeks pregnant with only a small amount of bleeding recommendations may include bed rest and avoiding sexual intercourse. For those after 36 weeks of pregnancy or with a significant amount of bleeding, cesarean section is generally recommended. In those less than 36 weeks pregnant, corticosteroids may be given to speed development of the babies lungs. Cases that occur in early pregnancy may resolve on their own.

It affects approximately 0.5% of pregnancies. After four cesarean section it, however, effects 10% of pregnancies. Rates of disease have increased over the late 20th century and early 21st century. The condition was first described in 1685 by Paul Portal.

The seizures of eclampsia typically present during pregnancy and prior to delivery (the antepartum period), but may also occur during labor and delivery (the intrapartum period) or after the baby has been delivered (the postpartum period). If postpartum seizures develop, it is most likely to occur within the first 48 hours after delivery. However, late postpartum seizures of eclampsia may occur as late as 4 weeks after delivery.

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.