Even if adolescent pregnancy rates are declining in the western world, a health care provider approaching an adolescent girl seeking for medical assistance must always be aware that she could be at risk of early pregnancy and the subsequent practical suggestions must be considered:
Pregnancy test: it is mandatory in cases of amenorrhea, abdominal pains, nausea, vomiting, weight gain, urinary dysfunctions, menstrual disorders whatever sexual history is reported
First-trimester ultrasonography is necessary to check gestational age if pregnancy test is positive
Careful counselling about all available options: to be supplied with a nonjudgmental attitude if a pregnancy is diagnosed. The gestational age being verified, health care provider must deal with all possible choices (parenting, termination, fostering, adoption) according to the current laws of the country
Privacy and confidentiality should be guaranteed at most
Close follow-up and support: they must be supplied by devoted facilities and specialized health care providers whatever the choice is
Multidisciplinary approach is advisable at most, considering adolescence is a distinct physical and developmental stage in woman’s life and teen pregnancy worldwide shows higher maternal, obstetrical, and neonatal risks. Therefore, adolescent gestations should be managed as high risk ones. Gynecologist and devoted midwives, social workers, psychologists, and support groups should take care of the adolescent mothers [12, 13]
Postpartum or post-termination contraception planning is mandatory to be already established when the pregnancy is still in progress 
Abortion in adolescents is differently regulated in various countries according to local laws; therefore, a comprehensive dissertation of its management is almost impossible and beyond the scope of the present treatise, which is mostly focused on the continuation of pregnancy and the connected items.
If the adolescent’s choice is parenting, it is worth stressing that teen pregnancy entails heavy risks both for the mother and the fetus because of typical biological, social, environmental, and behavioral features (mostly predisposing to preterm delivery and low birth weight infants), all of which deserve special consideration. Teen pregnancy should therefore be managed as a high risk one in programs taking care of its unique features and concerns . The subsequent typical adolescent biological items must be carefully considered.
Maternal age at conception: even if previous experiences highlighted adolescent mothers aged less than 16 years to be at high risk of preterm delivery and low birth weight neonates  more recent researches defined:
“Young maternal age” as low gynecological age (≤2 years since menarche) or as a chronological age ≤16 years at conception or delivery
“Very young maternal age” as gynecological age <2 years postmenarche or as a chronological age <15 years at conception or delivery
Gynecologic age, mentioned above, is defined as: age at last menstrual period minus age at menarche. Considering 2–3 postmenarchal years are required to reach full reproductive maturation; reproductive immaturity was defined as gynecologic age less than 3 years , now updated as a gynecologic age less than 2 years. In fact, body height and pelvic development are almost complete by 2 years after menarche . During this interim, a conception may occur in still growing reproductive organs, predisposing to preterm delivery .
Maternal prepregnant size, i.e., BMI, is a reliable predictor of infant size at birth, with small mothers delivering small offsprings. Defining low prepregnant weight as <45 kg and short prepregnant stature as <157 cm, a less than 19.8 kg/m2 BMI reveals a thin body habitus, with an increased risk of low birth weight babies, possibly due to a deficit in both visceral adiposity, which is a determinant of insulin resistance, and in subcutaneous truncal adipose tissue during the first 2 postmenarchal years .
Cervix length, defined as the shortest distance between the internal cervical os and the external one, in adolescent mothers may be shorter than in older women because of still incomplete development, thus predisposing to preterm delivery when a distance <25 mm is detected prior of 29 weeks gestation [17, 20]. Shorter cervices may also predispose to lower genital tract infections, which are more frequent in adolescents with a further increased risk of preterm delivery. During pregnancy, cervical length should be verified by serial transvaginal ultrasonic scans.
Gravidity and parity: as opposed to what happens in adults, repeated adolescent pregnancies show a growing risk of preterm delivery .
Fetomaternal competition for nutrients, occurring between the still growing mother and her fetus, may explain the reason why pregnant teens gain more weight during pregnancy and deliver smaller babies than older women do. The needs of both growing mother and fetus cannot simultaneously be satisfied and a competition for nutrients occurs between each other resulting in higher incidence of both poor fetal growth and maternal anemia . Leptin surges in the third trimester, hyperinsulinemia, insulin resistance may lead to continuous storage of maternal fat reserves, making less energy available for the fetus with subsequent smaller placenta, less placental nutrient transfer, and reduced uterine/umbilical cord blood transfer and IUGR .
To prevent preterm delivery and low birth weight babies, health care providers dealing with pregnant teens must focus their attention on the below reported items:
Gestational weight gain, defined as the difference between the last measured weight gain in pregnancy and the reported prepregnant weight is a reliable predictor of the infant birth weight mainly in adolescents because of their typical perimenarchal weight gain at central body areas .
Past history of preterm delivery: it raises the risk of a subsequent premature birth mainly if repeated pregnancies occur in under 18 year olds .
Genitourinary tract infections are well-known preterm delivery inducers in all ages pregnancies by favorising chorioamnionitis and by damaging the connective tissue of the cervix and the placental membranes through microbic proteases, elastases, collagenases, and mucinases leading to pPROM. In pregnant teens, the alkalinity of the peripubertal vagina may increase their susceptibility to bacterial vaginosis; the eversion of the squamocolumnar junction of the adolescent cervix may foster Chlamydia infections, of which the incidence is quite high in this population group, ranging from 11.8 to 31% . Finally, the typical shorter cervix may enhance the ascending of vaginal organisms to the upper uterus . Besides the physiological features of pubertal status, the adolescent sexual behaviors, typified by serial unprotected monogamous sexual relations with low condom use, make pregnant teens frequently acquire the sexually transmitted diseases fostering preterm prelabor rupture of membrane (pPROM) and subsequent preterm delivery . Besides the reported higher risk of pPROM and preterm delivery, in pregnant teens STDs increase also the risk of HIV acquisition and transmission .
Trauma is the main cause of death in adolescence. Pregnant teens suffer from accidental and non-accidental traumas more than older women do . In pregnant teens, abdominal traumas are very frequent, rising the risk of placental abruption and preterm delivery, making it mandatory to screen for recent traumas in a teen pregnancy care setting .
As previously stated, social and demographic features, as well as behavioral and psychological variables, are important factors in the risk assessment of a pregnant teen and in the subsequent follow-up.
Ethnicity is closely related to early pregnancy, with American black and hispanic women having the highest pregnancy rates and white non-hispanic women having the lowest ones . Black race also strongly raises the risk of preterm and very preterm deliveries both in adults and adolescent mothers (while hispanic ethnicity does not), possibly because of increased, ethnicity-connected, susceptibility to bacterial vaginosis, group B streptococcal infection, and premature cervical effacement .
Socioeconomic status plays a main role both in fostering teen pregnancies and in conditioning their outcome, with higher rates of preterm delivery among poor teen mothers. Some experiences showed that pregnant teenagers were more likely to be single and to live in a rural area , other researches detected higher pregnancy rates among ethnic minorities living in deprived metropolitan areas , among underachievers in school and among young women with mental health problems . Very often teen mothers belong to a single-parent family or have parents poorly interested in their education. Having a low educated mother or being herself a teen mother increases the risk of adolescent pregnancy, the same as being a younger sibling of an adolescent mother . Unemployment and child poverty are also strong predisposing factors, and the trend is “the lower the deprivation rank, the higher the risk of teenge pregnancy” .
Inadequate nutrition: Even if a proper nutrition is of utmost importance during teenage because of growth and physical changes, the diet quality is usually poor in adolescents, whose primary sources of macronutrients are often foods lacking nutritional properties . Pregnant teens show the same food preferences, eating behaviors, and lifestyle habits of their nonpregnant peers . If compared with women aged 19–64, girls aged 11–18 consume less fruits and vegetables with higher intakes of sugar-sweetened beverages and inadequate intake of key vitamins and minerals. Such dietary patterns are similar across highly developed countries . Adolescent girls are at particular risk of iron deficiency anemia due to both the rapid growth in teenage and the onset of menarche . The iron needs linked to adolescence coupled with the increased iron demand in pregnancy makes pregnant adolescent particularly vulnerable, and iron deficiency is aknowledged to be implicated in adverse birth outcomes such as prematurity and low birth weight . As well known, good pregnancy nutrition plays an important role on birth outcomes, fetal growth, and infant survival. Nutritionl needs change during the course of pregnancy with increasing requirements for several micronutrients as the pregnancy progresses . Conversely, pregnant adolescents were shown to have intakes of energy, iron, folate, calcium, Vitamin E, and magnesium below the dietary recommendations [37, 38]. If compared with older teens, “very young adolescents” (under 15 years or under 2 years gynecological age) may be at even greater nutritional risk due to competing growth needs between mother and fetus . Smoking teen gravidas and those from deprived backgrounds may also be at greater risks of nutritional issues [39, 40]. Compliance for supplements may be low in pregnant teens .
Substance abuse: According to large cohort studies, tobacco smoking, drugs, and alcohol misuse are more frequent among teen mothers than in pregnant women aged 25–30 . Sigarette smoking during the first trimester entails an increased risk of miscarriage and labio-palatoschisis while smoking during the whole pregnancy (the same as heavy second hand smoke) implies higher incidences of preterm delivery, low birth weight babies SIDS and future smoking offsprings, mainly if they are females. Attention-Deficit/Hyperactivity Disorder (ADHD) and asthma are also more frequent among children of smoking pregnant teens. Smoking reduction programs for pregnant adolescents were more successful when smoking partners are also involved . Alcohol misuse is epidemic among adolescents, and it is quite common also among pregnant teens. Both alcohol moderate daily assumption and occasional drunknesses during the first trimester raise the risk of miscarriage, intra uterine fetal death, and a range of lifelong physical, cognitive, and behavioral birth defects, such as IUGR, microcephaly, facial dismorphologies (short palpebral fissures, thin upper lip, smooth filtrum), and various central nervous system dysfunctions, all grouped under the umbrella name of fetal alcohol spectrum disorders (FASD) [42, 43]. Considering FASD are mostly due to a fetal alcohol exposure between the sixth and 12th week of gestation, they are only partially preventable at the first antenatal visit. International guidelines recommend temperance during the first trimester of gestation but even in the subsequent trimesters a security threshold is not specified because of individual alcohol metabolization . Pregnant teens may be multiple illicit substances addicts, each one with different dangerous effects (summarized in the Table 15.1), but all of them sharing a common increased risk of preterm delivery and IUGR.
Effects of prenatal exposure to abuse substances 
Effects on fetus and pregnancy
Other long-distance effects
Cannabis and cannabinoids
Ectopic pregnancy, IUGR, preterm delivery
Risk of SIDS
Short term and visuo-spatial memory defects
Higher risk of tobacco and cannabis smoking offsprings
Defective verbal and attentive abilities
Low body length and weight
Higher sensitivity to stressors
Overweight in babyhood
Altered placental vessels with preeclampsia and abruptio placentae
Risk of necrotizing enterocolitis
IUGR, preterm delivery
Urogenital and cardiac anomalies
Low linear growth in second childhood
Amfetamine and derivates
Low birth weight
Low APGAR score
Anxiety and depression in childhood
Low motor ability
Low verbal memory
Abruptio placentae due to untreated withdrawal
Neonatal withdrawal syndrome
Neurodevelopmental and behavioral disorders
Inhalants: gases, solvents, aerosols, nitrites
History of childhood abuse: A history of sexual and physical abuse places female adolescent at increased risk of becoming pregnant, fostering early sexualization, initiation, sexual risk-taking behaviors, and promiscuity . In the main, exposure to all types of abuse increases the likelihood to start intercourses at early age and promotes low self-esteem and association with deviant peer groups: all factors leading to premature pregnancies . The strength of this association varies with abuse type. Higher risk of adolescent pregnancy was verified following sexual and physical abuse but not in cases of emotional abuse and neglect. The co-occurrence of both physical and sexual abuse was even stronger than any single kind of abuse, with a fourfold increased risk of early pregnancy . Among previously abused adolescents pregnancy may be not unplanned: a desire to escape from an abusive or dysfunctional family and to create a new family environment may lead to early pregnancy . Previously abused pregnant adolescents are more likely to be cigarette smokers and alcohol or illicit substances addicts. They are also more often sexually promiscuous and involved in coercive sex, with higher risks of STDs and injury-mediated preterm delivery [16, 19]. Teen mothers who have been victims of abuse show higher risk of seeking late antenatal care, poorer obstetrical outcomes, increased neonatal morbidity and of committing sexual abuse during their own child’s life [45–47]. Moreover, if a history of previous sexual abuse doubles, the risk of adolescent pregnancy in a girl, a fivefold increase of pregnancy involvement was verified in previously abused boys . Sexual abuse and violence before and during pregnancy should routinely be asked in an adolescent pregnancy setting .
School dropout: Undereducation is a sign of a set of psychosocial and medical risk factors; in fact, recreational drugs addiction, alcohol abuse, deviant behaviurs, preterm delivery are more common among pregnant teens who dropout of school. By leaving school, these girls also loose an important source of support which could help them to develop the sense of mastery required to face motherhood [16, 19].
Mood disorders: Psychopathology in teenagers is a risk factor for early pregnancy. Sixteen to 44% pregnant teens show depressive symptoms which worsen between the second and the third trimester, with an incidence twice as high as among adult gravidas and nonpregnant adolescents [50, 51]. Adolescent perinatal depression is strongly associated with low socioeconomic status and lacking social support . Furthermore, previous experiences revealed postpartum depression in half adolescent mothers, i.e., twice the rate of adult mothers . If untreated, maternal depression is associated with adverse maternal, neonatal, and childhood outcomes, with higher incidence of preterm delivery, SGA infants and behavioral and cognitive disorders in children as well. Postpartum depression, unresponsive mothering, and rapid repeated pregnancy often occur in depressed pregnant teens [54, 55] with frequent postpartum smoking, alcohol misuse, and substance abuse .
Adolescent pregnancies have a higher risk of adverse outcomes  and besides age-related risk factors pregnant teens show typical maternal, obstetric, and neonatal complications during gestation and at delivery, of which it is worth mentioning:
Anemia and nutritional deficiencies: Because of feto-maternal competition for nutrients and increased postmenarchal needs anemia is very frequent among pregnant adolescents, being detected in 50–66% cases . Besides the above-mentioned deficiencies of micronutrients, because of mostly unplanned gestations, precoceptional counselling and folic acid supplementation are often missed in pregnant teens, whose age implies a slowly higher risk of spina bifida. Eating habits, cigarette smoking, alcohol consumption, and some gastrointestinal diseases, such as celiac disease, atropic gastritis, Crohn’s disease, and ulcerative colitis, may impair the intestinal absorption of folate, the same as the administration of trimethoprim, pyrimethamine, antiepileptic drugs, aminopterin, methotrexate, sulfasalazine, and isotretinoin . All the above-mentioned clinical and behavioral situations, and also MTHFR gene polymorphism, require an implemented 5 mg daily folic acid supplementation instead of the usually recommended 400 μg daily administration . Furthermore, because of poor outdoor activities, Vitamin D blood levels were shown to be low in many adolescents, mainly if they are black, vegan, on a low fat diet, overweight, or obese. Type 1 diabetes, inflammatory bowel diseases, liver diseases, cystic fibrosis, African or Southern Asian ethnicities, long lasting treatments with heparine, isotretinoin, glucocorticoids, antituberculous, and antiepileptic drugs may also lower Vitamin D availability, and its deficiency could promote preeclampsia and impair the skeletal and dental development of the fetus. Daily Vitamin D 100 UI, equal to 10 μg, is needed in pregnancy. Either daily 15 minutes sun exposure of arms and face or Vitamin D supplementation are recommended in pregnancy .
Eating habits and BMI: Teen pregnancies may occur in girls suffering from eating disorders while they improve their food supply. A low BMI, as defined by proper age-related diagrams, raises the risk of LBW newborns and preterm delivery due to pPROM. Eating habits must be strictly monitored in pregnant teens, considering also a high preconceptional BMI and high-fat diets raise the risk of both macrosomia and preeclampsia . Total and average physiologic weight gain related to preconceptional BMI is reported in Table 15.2.
Total and average physiologic weight gain related to preconceptional BMI
Preconceptional BMI (kg/m2)
Total weight gain
Second and third trimester average weight gain (kg/week)
<18.5 → underweight
18.5–24.9 → normal weight
25–29.9 → overweight
>30 → obesity
Insufficient prenatal care: if compared with older pregnant women, adolescents were shown to start their prenatal care significantly later in pregnancy, with delayed or missed first trimester antenatal visits and also significantly lower attendance rate of prenatal classes [2, 46]. Reasons for delay in seeking care lie on lacking knowledge about the relevance of prenatal care and about the consequences of its missing. Previous violence, desire to hide pregnancy, doubts about continuation, concerns about lack of privacy or judgmental attitudes from health care providers, financial problems may be further reasons behind the delay. Absent or delayed prenatal care worsens maternal, obstetrical, and neonatal outcomes .
Preeclampsia and hypertensive disorders of pregnancy: available data about their incidence in teens are controversial. Some studies reported a higher incidence than in adults, possibly connected to the reproductive and physiologic immaturity of pregnant adolescents [16, 19, 62]. Other experiences do not demonstrate any difference  or even showed reduced rates after potential confounders being controlled . Very common risk factors of preeclampsia in teens are nulliparity and first pregnancy with a partner . Screenings of preeclampsia are available at first trimester by combining blood pressure assessment, ultrasonography, and seric PAPP-A levels at the second trimester by performing Doppler ultrasonography of maternal uterine arteries.
Congenital anomalies are more common in adolescent pregnancies, with higher rates of CNS anomalies (anencephaly, spina bifida, hydrocephaly, microcephaly), gastrointestinal anomalies (gastroschisis, omphalocele), and musculoskeletal anomalies (cleft lip, cleft palate, polydactily, syndactaly) , possibly due to pre- and postconceptional risky behaviors or to nutritional deficiencies . A careful second trimester ultrasonographic screening of fetal anomalies must be supplied.