is closed indicating that conception products will pass in the near future. missed: vaginal bleeding occurs and some products of conception may have passed through the cervix; the cervical os is closed and ultrasound shows a nonviable fetus and remaining products of conception. threatened: vaginal bleeding occurs; the cervical os is closed and ultrasound shows a viable fetus. stillbirth stillbirth is defined as fetal loss or death after 20 weeks gestation. early stillbirth is between 20 and 27 weeks gestation, while late stillbirth is between 28 and 36 weeks gestation. a term stillbirth is when the fetus dies 37 weeks and above. epidemiology: there are over 2 million stillbirths a year and there are about 6 stillbirths per 1000 births (0.6%) clinical presentation: fetal behavioral changes like decreased movements or a loss in fetal sensation may indicate stillbirth, but the presentation can vary greatly. risk factors: maternal weight, age, and smoking, as well as pre-existing maternal diabetes or hypertension treatment: if fetal passing occurs before labor, treatment options include induced labor or cesarean section. otherwise, stillbirths can pass with natural birth. placental abruption placental abruption defined as the separation of the placenta from the uterus prior to delivery, is a major cause of third trimester vaginal bleeding and complicates about 1% of pregnancies. clinical presentation: varies widely from asymptomatic to vaginal bleeding and abdominal pain. risk factors: prior abruption, smoking, trauma, cocaine use, multifetal gestation, hypertension, preeclampsia, thrombophilias, advanced maternal age, preterm premature rupture of membranes, intrauterine infections, and hydramnios. treatment: immediate delivery if the fetus is mature (36 weeks or older), or if a younger fetus or the mother is in distress. in less severe cases with immature fetuses, the situation may be monitored in hospital, with treatment if necessary. placenta previa placenta previa is a condition that occurs when the placenta fully or partially covers the cervix. placenta previa can be further categorized into complete previa, partial previa, marginal previa, and low-lying placenta, depending on the degree to which the placenta covers the internal cervical os. placenta previa is diagnosed by ultrasound, either during a routine examination or following an episode of abnormal vaginal bleeding. most diagnosis of placenta previa occurs during the second-trimester. risk factors: prior cesarean delivery, pregnancy termination, intrauterine surgery, smoking, multifetal gestation, increasing parity, maternal age. placenta accreta placenta accreta is an abnormal adherence of the placenta to the uterine wall. specifically, placenta accreta involves abnormal adherence of the placental trophoblast to the uterine myometrium. placenta accreta risk factors include placenta previa, abnormally elevated second-trimester afp and free β-hcg levels, and advanced gestational parent age, specifically over the age of 35. furthermore, prior cesarean delivery is one of the most common risk factors for placenta accreta, due to the presence of a uterine scar leading to abnormal decidualization of the placenta. due to abnormal adherence of the placenta to the uterine wall, cesarean delivery is often indicated, as well as cesarean hysterectomy. multiple pregnancies main article: multiple birth multiple births may become monochorionic, sharing the same chorion, with resultant risk of twin-to-twin transfusion syndrome. monochorionic multiples may even become monoamniotic, sharing the same amniotic sac, resulting in risk of umbilical cord compression and entanglement. in very rare cases, there may be conjoined twins, possibly impairing function of internal organs. mother-to-child transmission further information: vertically transmitted infection further information: neonatal infection since the embryo and fetus have little or no immune function, they depend on the immune function of their mother. several pathogens can cross the placenta and cause (perinatal) infection. often microorganisms that produce minor illness in the mother are very dangerous for the developing embryo or fetus. this can result in spontaneous abortion or major developmental disorders. for many infections, the baby is more at risk at particular stages of pregnancy. problems related to perinatal infection are not always directly noticeable. the term torch complex refers to a set of several different infections that may be caused by transplacental infection: t - toxoplasmosis o - other infections (i.e. parvovirus b19, coxsackievirus, chickenpox, chlamydia, hiv, htlv, syphilis, zika) r - rubella c - cytomegalovirus h - hsv babies can also become infected by their mother during birth. during birth, babies are exposed to maternal blood and body fluids without the placental barrier intervening and to the maternal genital tract. because of this, blood-borne microorganisms (hepatitis b, hiv), organisms associated with sexually transmitted disease (e.g., gonorrhoea and chlamydia), and normal fauna of the genito-urinary tract (e.g., candida) are among those commonly seen in infection of newborns. general risk factors factors increasing the risk (to either the pregnant individual, the fetus/es, or both) of pregnancy complications beyond the normal level of risk may be present in the pregnant individual's medical profile either before they become pregnant or during the pregnancy. these pre-existing factors may related to the individual's genetics, physical or mental health, their environment and social issues, or a combination of those. biological some common biological risk factors include: age of either parent adolescent parents: young mothers are at an increased risk of developing certain complications, including preterm birth and low infant birth weight. older parents: as they age, both mothers and fathers are at an increased risk for complications in the fetus and during pregnancy and childbirth. complications for those 45 or older include increased risk of primary caesarean delivery (i.e. c-section). height: pregnancy in individuals whose height is less than 1.5 meters (5 feet) correlates with a higher incidence of preterm birth and underweight babies. also, these individuals are more likely to have a small pelvis, which can result in such complications during childbirth as shoulder dystocia. weight low weight: individuals whose pre-pregnancy weight is less than 45.5 kilograms (100 pounds) are more likely to have underweight babies. high weight: obese individuals are more likely to have very large babies, potentially increasing difficulties in childbirth. obesity also increases the chances of developing gestational diabetes, high blood pressure, preeclampsia, experiencing postterm pregnancy and requiring a cesarean delivery. pre-existing disease in pregnancy, or an acquired disease: a disease and condition not necessarily directly caused by the pregnancy. diabetes mellitus in pregnancy lupus in pregnancy thyroid disease in pregnancy risks arising from previous pregnancies: complications experienced during a previous pregnancy are more likely to recur. multiple pregnancies: individuals who have had greater than five previous pregnancies face increased risks of rapid labor and excessive bleeding after delivery. multiple gestation (having more than one fetus in a single pregnancy): these individuals have an increased risk of mislocated placenta. environmental some common environmental risk factors during pregnancy include: exposure to environmental toxins ionizing radiation exposure to recreational drugs alcohol: use during pregnancy can cause fetal alcohol syndrome and fetal alcohol spectrum disorder. tobacco use: during pregnancy, causes twice the risk of premature rupture of membranes, placental abruption and placenta previa. also, it increases the odds of the baby being born prematurely by 30%. prenatal cocaine exposure: associated with premature birth, birth defects and attention deficit disorder. prenatal methamphetamine exposure: can cause premature birth and congenital abnormalities. other investigations have revealed short-term neonatal outcomes to include small deficits in infant neurobehavioral function and growth restriction when compared to control infants. also, prenatal methamphetamine use is believed to have long-term effects in terms of brain development, which may last for many years. cannabis: possibly associated with adverse effects on the child later in life. social and socioeconomic factors: generally speaking, unmarried individuals and those in lower socioeconomic groups experience an increased level of risk in pregnancy, due at least in part to lack of access to appropriate prenatal care. unintended pregnancy: unintended pregnancies preclude preconception care and delays prenatal care. they preclude other preventive care, may disrupt life plans and on average have worse health and psychological outcomes for the mother and, if birth occurs, the child. exposure to pharmaceutical drugs: certain anti-depressants may increase risks of preterm delivery. high-risk pregnancy 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 reproductive organs, some of which are listed above) and diseases acquired at any time during the woman's life. absolute and relative incidence of venous thromboembolism (vte) during pregnancy and the postpartum period absolute incidence of first vte per 10,000 person–years during pregnancy and the postpartum period swedish data a swedish data b english data danish data time period n rate (95% ci) n rate (95% ci) n rate (95% ci) n rate (95% ci) outside pregnancy 1105 4.2 (4.0–4.4) 1015 3.8 (?) 1480 3.2 (3.0–3.3) 2895 3.6 (3.4–3.7) antepartum 995 20.5 (19.2–21.8) 690 14.2 (13.2–15.3) 156 9.9 (8.5–11.6) 491 10.7 (9.7–11.6) trimester 1 207 13.6 (11.8–15.5) 172 11.3 (9.7–13.1) 23 4.6 (3.1–7.0) 61 4.1 (3.2–5.2) trimester 2 275 17.4 (15.4–19.6) 178 11.2 (9.7–13.0) 30 5.8 (4.1–8.3) 75 5.7 (4.6–7.2) trimester 3 513 29.2 (26.8–31.9) 340 19.4 (17.4–21.6) 103 18.2 (15.0–22.1) 355 19.7 (17.7–21.9) around delivery 115 154.6 (128.8–185.6) 79 106.1 (85.1–132.3) 34 142.8 (102.0–199.8) – postpartum 649 42.3 (39.2–45.7) 509 33.1 (30.4–36.1) 135 27.4 (23.1–32.4) 218 17.5 (15.3–20.0) early postpartum 584 75.4 (69.6–81.8) 460 59.3 (54.1–65.0) 177 46.8 (39.1–56.1) 199 30.4 (26.4–35.0) late postpartum 65 8.5 (7.0–10.9) 49 6.4 (4.9–8.5) 18 7.3 (4.6–11.6) 319 3.2 (1.9–5.0) incidence rate ratios (irrs) of first vte during pregnancy and the postpartum period swedish data a swedish data b english data danish data time period irr* (95% ci) irr* (95% ci) irr (95% ci)† irr (95% ci)† outside pregnancy reference (i.e., 1.00) antepartum 5.08 (4.66–5.54) 3.80 (3.44–4.19) 3.10 (2.63–3.66) 2.95 (2.68–3.25) trimester 1 3.42 (2.95–3.98) 3.04 (2.58–3.56) 1.46 (0.96–2.20) 1.12 (0.86–1.45) trimester 2 4.31 (3.78–4.93) 3.01 (2.56–3.53) 1.82 (1.27–2.62) 1.58 (1.24–1.99) trimester 3 7.14 (6.43–7.94) 5.12 (4.53–5.80) 5.69 (4.66–6.95) 5.48 (4.89–6.12) around delivery 37.5 (30.9–44.45) 27.97 (22.24–35.17) 44.5 (31.68–62.54) – postpartum 10.21 (9.27–11.25) 8.72 (7.83–9.70) 8.54 (7.16–10.19) 4.85 (4.21–5.57) early postpartum 19.27 (16.53–20.21) 15.62 (14.00–17.45) 14.61 (12.10–17.67) 8.44 (7.27–9.75) late postpartum 2.06 (1.60–2.64) 1.69 (1.26–2.25) 2.29 (1.44–3.65) 0.89 (0.53–1.39) notes: swedish data a = using any code for vte regardless of confirmation. swedish data b = using only algorithm-confirmed vte. early postpartum = first 6 weeks after delivery. late postpartum = more than 6 weeks after delivery. * = adjusted for age and calendar year. † = unadjusted ratio calculated based on the data provided. source: list of complications (complete) obstetric complications are those complications that develop during pregnancy. a woman may develop an infection, syndrome or complication that is not unique to pregnancy and that may have existed before pregnancy. pregnancy often is complicated by preexisting and concurrent conditions. though these pre-existing and concurrent conditions may have great impact on pregnancy, they are not included in the following list. chromosome abnormalities ectopic pregnancy mendelian disorders spontaneous abortion nonmedelian disorders oligohydramnios hydramnios abnormal labor and delivery chorioamnionitis shoulder dystocia breech delivery prior cesarean delivery uterine rupture hysterectomy after delivery postpartum infection postpartum depression septic pelvic thrombosis hypertension preeclampsia eclampsia placental abruption placenta previa fetal-to-mother hemorrhage rh disease amniotic fluid embolism delayed delivery fetal death incontinence preterm birth neonatal infection low birth-weight infant premature rupture of membranes incompetent cervix posterm infant fetal growth restriction macrosomia twin pregnancy triplets and more seizures gestational trophoblastic disease gestational diabetes hyperemesis gravidarum pelvic girdle pain hellp syndrome acute fatty liver of pregnancy deep vein thrombosis pregnancy-induced hypercoagulability immune tolerance in pregnancy mastitis peripartum cardiomyopathy vertically transmitted infection postpartum bleeding perineal tear fetal alcohol spectrum disorder thyroid disease in pregnancy pruritic urticarial papules and plaques of pregnancy intrahepatic cholestasis of pregnancy gestational pemphigoid prurigo gestationis lupus cephalopelvic disproportion stillbirth molar pregnancy obstetric fistula uterine incarceration twin to twin transfusion syndrome gestational trophoblastic disease antiphospholipid antibody syndrome hyperemesis gravidarum acute fatty liver of pregnancy gestational diabetes hemoglobinopathies postpartum thyroiditis postpartum depression hyperpigmentation hair growth changes herpes gestationitis pruritic urticarial papaules of pregnancy abnormality of maternal pelvic organs postpartum acute renal failure postpartum nephritis haemorrhoids in pregnancy obstetric embolism pregnancy-related peripheral neuritis obstetrical tetanus unicornuate uterus maternal death arcuate uterus