The risks of teen pregnancy including premature delivery, infants being small for gestational age, low birthweight and increased neonatal mortality, anaemia and pregnancy-induced hypertension.^{1994-01, 1995-01, 1996-01, 1999-01}

In the long term the offspring of adolescents have poorer cognitive development, lower educational attainment, more frequent criminal activity and a higher risk of abuse, neglect and behavioural problems during childhood. ^2002-01

Despite the magnitude of the problem, it is unknown whether the poor outcomes of teen pregnancy are partly attributable to the biological challenges presented by young maternal age or whether they are solely the consequence of sociodemographic factors. Sociodemographic variables associated with teen pregnancy undoubtedly increase the risk of adverse outcomes. However, recent studies have demonstrated that the relative risk remains significantly elevated for both younger and older teen mothers after adjustment for marital status, level of education and adequacy of prenatal care. ^2001-01

Gynaecological immaturity
The high risk of adverse pregnancy outcome in the adolescent has been attributed to gynaecological immaturity and the growth and nutritional status of the mother. Gynaecological immaturity undoubtedly predisposes adolescent girls to poor pregnancy outcome in that the rates of spontaneous miscarriage and of very preterm birth (<32 weeks of gestation) are highest in girls aged 13?15 years. However, maternal growth and nutritional status during pregnancy also appear to play a potentially modifiable role. Many adolescent girls retain the potential to grow while pregnant. Data from a study from Camden, New Jersey, ^1990-01 one of the poorest cities in the USA, has shown that almost 50% of adolescents continue to grow while pregnant. This growth is associated with larger pregnancy weight gains, increased fat stores and greater postpartum weight retention than in non-growing adolescents and mature women. Paradoxically, in spite of the changes typically associated with increased fetal size (larger pregnancy weight gains, increased fat stores), the offspring are smaller in growing than non-growing adolescents. This significant reduction in fetal growth rate is attributed to a competition for nutrients between the maternal body and the gravid uterus. Clearly, there is a complex interplay between socioeconomic and biological factors that influences the outcome of teen pregnancy.

Interestingly, while the incidence of teen pregnancy is declining in the UK, the proportion of teen girls smoking has remained unchanged and in some areas is increasing.^1995-02 This is an important clinical problem as smoking compounds the potential for adverse outcomes of adolescent pregnancy, particularly intrauterine growth restriction. The birthweight-for-gestational-age curves of smoking adolescents show a marked fall-off in weight from 36 weeks of gestation. Furthermore, at least 10% of adolescent smokers have pregnancies affected by severe early onset (before 32 weeks of gestation) fetal growth restriction.^2006-01

Smoking during pregnancy is also known to be associated with an increased risk of placental abruption, preterm premature rupture of membranes, preterm birth, stillbirth and sudden infant death syndrome. Research has shown that prenatal exposure to tobacco smoke is a risk factor for respiratory infections, asthma, allergy, childhood cancer and adverse neurobehavioural development. ^2004-01

The Centers for Disease Control and Prevention (CDCs) in the USA analysed state-specific trends in maternal smoking during 1990?2002. ^2004-02 This report indicated that participating areas observed a significant decline in maternal smoking during the surveillance period while 10 states reported recent increases in smoking by pregnant teens. The widespread public health message to abstain during pregnancy has helped decrease maternal smoking. To reduce prevalence further, implementation of additional interventions is required.

Teen pregnancy nutrition
Teens may have poor eating habits and neglect to take their vitamin supplements and even in teen pregnancy nutrition is poor. They are less likely than older women to be of adequate pre-pregnancy weight or to gain an adequate amount of weight during pregnancy. ^2003-02 Low weight gain increases the risk of having a low birthweight baby. This is frequently compounded by adverse social circumstances.

Postnatal depression and difficulties with breastfeeding.
There is evidence that teen mothers are more likely to suffer from postnatal depression than older mothers. ^1998-01 Furthermore, one study reported a 37?54% reduction in milk production 6 months after childbirth in adolescents compared with older mothers. ^1997-01

General measures
While there is no evidence, to date, of medical interventions that can specifically improve pregnancy outcome, we must ensure that teen mothers receive supportive care and are directed towards the social support they need. Smoking cessation should be targeted and attendance at an antenatal clinic encouraged. In addition, effective postnatal counselling, particularly regarding contraception, can help prevent subsequent pregnancies and STIs.

Termination of pregnancy and adoption
Teen pregnancy is often viewed as unplanned and unwanted. However, the reality is more complex. Although approximately 40% of teens in the UK terminate their pregnancies, the majority choose to continue. Over 25% will become pregnant again during their teen years, including 18% of those who terminate their first pregnancy. These figures suggest that many teens become pregnant by design rather than by accident.

While termination and adoption are options that are available and should be presented to the pregnant teen, the reality is that most girls choose to continue with their pregnancies and keep their infants. It is, therefore, imperative that every effort is made to encourage pregnant teens to access antenatal care and that the care they subsequently receive is tailored to the unique needs of this age group. The healthcare professional must be aware of the potential complications and the opportunities for intervention that exist.

Antenatal care
Adolescents should be encouraged to attend for antenatal care from an early stage as attendance is frequently poor. Gestational age should be confirmed with early ultrasound wherever possible, although many teens present late. This is an opportunity to offer advice on nutrition and adverse habits such as smoking and alcohol use. Social support is important and many teens may benefit from an early referral to a specialist midwife or social worker. Information regarding antenatal care and labour should be provided in a format that is accessible and easily understood. Caregivers should be sensitive to the potential challenges presented by written information, as a significant number of teens have literacy difficulties.

Care during labour and delivery
Where age is the only risk factor, management is usually the same as for other labouring women. However, in very young adolescents there is an increased likelihood of obstructed labour because of a small, immature pelvis.

Postnatal management
The postnatal period provides an opportunity for counselling and education from the obstetrician, midwife, general practitioner, health visitor and social worker. Teen mothers are more likely to have unhealthy habits that place the infant at greater risk of inadequate growth, infection and chemical dependence. Below the age of 20 years, the younger the mother, the greater the risk of her infant dying during the first year of life. Infant feeding, growth and safety need to be observed. Having her first child during adolescence makes a woman more likely to have more children overall. Women in this group are also less likely to receive child support from the biological fathers: over 50% of children of adolescent mothers never live with their biological father. ^1999-02 They are less likely to complete their education and establish the independence and financial security that enable them to provide for themselves and their children without outside assistance. There are, therefore, some areas that need special attention, particularly discussion regarding financial issues, returning to school and contraceptive advice.

Obstetric outcome of teenage pregnancies compared with adult pregnancies.(2008-01)

Adolescent smoking in pregnancy and birth outcomes. (2006-01)

Obstetric and perinatal outcomes in pregnancies associated with illicit substance abuse.(2004-01)

 Smoking during pregnancy--United States, 1990-2002. (2004-02)

Adolescent pregnancy. (2003-01)

Impact of maternal age and maternal somatic characteristics on newborn size.(2003-02)

Teen-aged mothers in contemporary Britain.(2002-01)

Does the increased risk of preterm delivery in teenagers persist in pregnancies after the teenage period?(2001-01)

Teenage pregnancies and risk of late fetal death and infant mortality.(1999-01)

The problem of teenage pregnancy.(1999-02)

Young maternal age and depressive symptoms: results from the 1988 National Maternal and Infant Health Survey.(1998-01)

Lactational performance of adolescent mothers shows preliminary differences from that of adult women.(1997-01)

Adolescence and very low birth weight infants: a disproportionate association.(1996-01)

Association of young maternal age with adverse reproductive outcomes.(1995-01)

Prenatal care and maternal health during adolescent pregnancy: a review and meta-analysis.(1994-01)

Maternal growth during pregnancy and decreased infant birth weight.(1990-01)