Preconception and Prenatal Care

Maternal Age Over 35 Years

With advancing maternal age comes an increased likelihood of preexisting chronic medical diseases such as arthritis, hypertension, and diabetes. The national Maternity Experiences Survey of the Canadian Perinatal Surveillance System found that nulliparous women aged 35 years and over are significantly more likely to have had a miscarriage or infertility treatment, to request or be offered a cesarean delivery (CD), and to have a higher rate of CD than primiparous women aged 20 to 29 years, but they are not at higher risk for PTB, LBW, or small-for-gestational-age (SGA) infants. A recent systematic review and meta-analysis study found that age over 35 increased the risk of stillbirth (OR, 1.75; 95% CI, 1.62–1.89), preeclampsia (OR 1.99; 95% CI, 1.65–2.36), neonatal death (OR, 1.48; 95% CI, 1.30–1.67), NICU admission (OR, 1.49; 95% CI, 1.34–1.66), and gestational diabetes mellitus (GDM) (OR, 2.85; 95% CI, 2.46–3.32 ⁾ . These risks increase with advancing maternal age and the rates of preeclampsia and GDM almost double in women aged 50 years or more, and the vast majority of them can expect to deliver via CD.

Many nulliparous women aged 40 and over require the use of artificial reproductive technologies (ART) to become pregnant. Women over 35 who conceived with ART are more likely to proceed with an elective CD and are at increased risk of retained placenta compared with women over 35 who conceive spontaneously. In older women, ART techniques may require oocyte donation, which has been associated with increased risks of preeclampsia and premature delivery. A recent systematic review and meta-analysis of 35 studies has found that the risk of preeclampsia as evaluated by adjusted odds ratio (aOR) was 2.11 (95% CI, 1.42–3.15) in singleton and 3.31 (95% CI, 1.61–6.80) in multiple pregnancies. The risks of PTB and LBW in singletons were aOR 1.75 (95% CI, 1.39–2.20) and 1.53 (95% CI, 1.16–2.01), respectively. Furthermore, as a result of ART, the twin birth rate to women aged 40–44 nearly doubled between 1990 and 2001, and that of triplets increased fourfold in women 35 years and older between 1975 and 1998. Within this context, in particular in older women with a preexisting medical condition, reproductive medicine subspecialists, maternal fetal medicine subspecialists, and obstetrician/gynecologists should promote more realistic views of the evidence-based realities of pregnancy in women over 35.

Teen Pregnancies

The true prevalence of teen pregnancy worldwide is difficult to determine because of incomplete data but estimates suggest it occurs in 13% of the US population and 25% worldwide. In a comprehensive review by Sedgh et al., there were 21 countries with complete statistics revealing that the pregnancy rate among 15- to 19-year-olds was highest in the US (57/1000), and lowest in Switzerland (8/1000). It is believed that rates are higher in Mexico and sub-Saharan Africa but there is incomplete reporting. A Swedish survey found that adolescents are more likely to be delivered vaginally than older women and that the risks of placenta previa, postpartum hemorrhage (PPH), and perineal lacerations are lower for adolescents than for adult women. However, adolescents have increased risk of preeclampsia, PTB, LBW, and pregnancy loss including neonatal and infant mortality, stillbirths, intrapartum deaths, and miscarriages. The younger the patient, the greater the risk for both mom and baby. Globally, complications from childbirth are the second leading cause of mortality in the 15- to 19-year-old age group.

Adolescent pregnancy is often unplanned (80%) and has a negative impact on the physical, emotional, educational, and economic condition of the pregnant teenager. This high rate of unintended pregnancy is associated with a high abortion rate. Approximately 50% of teen pregnancies lead to abortions. Adolescent parenthood is associated with a range of adverse outcomes for young mothers, including mental health problems such as depression, substance abuse, and posttraumatic stress disorder. Adolescents are also more likely to smoke (36% vs. 7%), drink alcohol or use drugs (1.1% vs. 0.2%), as well as have higher levels of emotional stress, partner violence and abandonment, and unstable or unsafe home environments compared to adults. Teen mothers are more likely to be impoverished and to reside in communities and families that are socially and economically disadvantaged, which likely is a contributing factor to their higher risk of delivering prematurely.

In middle- and low-income countries, higher risks of preterm delivery have also been demonstrated for adolescent mothers aged 10 to 19 years. In addition, their risk of eclampsia, puerperal endometritis, emergency CD, PPH, and systemic infections is higher compared with mothers aged 20 to 24 years. These worldwide consistent trends stress the important role of health care workers as health policy advocates to ensure that all teenagers receive sound sex education in school programs and that family planning agencies are permitted to counsel teenagers and provide contraception services that include medications and long-acting reversible contraception devices. The importance of family planning and access to contraception for teens cannot be overstated, as there is a high rate of rapid repeat pregnancy within 1 to 2 years.

Weight Gain

Weight gain during pregnancy has been shown to be an important predictor of pregnancy outcome (see Chapter 6 ). Maternal weight gain correlates with fetal weight gain and is, therefore, closely monitored. Too little weight gain should lead to an evaluation of nutritional factors and an assessment of associated fetal growth. Excess weight gain is one of the first signs of fluid retention, but it may also reflect increased dietary intake or decreased physical activity. The trajectory of weight gain in the second and third trimester is an important predictor of birthweight.

In the US, the total weight gain recommended in pregnancy is 11 to 16 kg (25–35 lb) for women at a healthy weight. Underweight women can gain up to 18 kg (40 lb), but overweight women should limit weight gain to 7 kg (15 lb), although they do not need to gain any weight if they are morbidly obese.

At term, the typical woman gains about 3 to 4 kg (7–9 lb) from increased tissue fluid volume and fat, 1.5 to 2 kg (3–4 lb) from increased blood volume, 0.5 to 1 kg (1–2 lb) from breast enlargement, 1 kg (2 lb) from enlargement of the uterus, 1 kg or 1 L (2 lb) from amniotic fluid, 2.7 to 3.6 kg (6–8 lb) for the fetus, and 0.5 to 1 kg (1–2 lb) of placental weight. Usually, 1.4 to 2.7 kg (3–6 lb) are gained in the first trimester, and 0.2 to 0.6 kg (0.5–1 lb) per week are gained during the last two trimesters of pregnancy.

If the patient does not show a 4.5 kg (10 lb) weight gain by mid pregnancy, her nutritional status should be reviewed. Inadequate weight gain is associated with an increased risk of an LBW infant. Inadequate weight gain seems to have its greatest effect in woman at a healthy weight or those who are underweight before pregnancy. Underweight mothers must gain more weight during pregnancy to produce infants of normal weight. In overweight and obese women, weight loss or gain of 11 lb (5 kg) or less is associated with increased risk of an SGA infant and decreased neonatal fat mass, lean mass, and head circumference.

When excess weight gain is noted, patients should be counseled to avoid foods that are high in fats and carbohydrates, to limit sugar intake, and to increase their physical activity. Several small studies suggest that monitoring weight gain, quantity of food consumed, and physical activity combined with behavioral counseling can limit weight gain during pregnancy and promote postpartum weight loss.

Dietary and lifestyle interventions in pregnancy can reduce maternal gestational weight gain and improve outcomes for both mother and baby. Among the interventions, those based on diet are the most effective and are associated with reductions in maternal gestational weight gain and improved obstetric outcomes. Most obstetric providers are aware of these recommendations, but many do not feel comfortable making treatment recommendations.

Weight gain and weight retention after pregnancy is a risk factor for subsequent obesity. Thus postpartum weight loss should be encouraged. Women who resumed their prepregnancy weight by 6 months postpartum gained only 2.4 kg (5 lb) over the next 10 years compared with 8.3 kg (18 lb) for women who retained weight after delivery. It has been estimated that 40% to 60% of normal and overweight women gain more than the Institute of Medicine recommendations making postpartum weight loss difficult. Data suggest that 75% of women are heavier than their prepregnancy weight 1 year postpartum, and weight retention between the first and second pregnancy is associated with an increased risk for perinatal complications, even in underweight and normal-weight women.

Stabilizing interpregnancy weight appears to be an important target to avoid adverse perinatal outcomes in a second pregnancy. Although clinicians have focused on teaching women that appropriate weight gain is important for pregnancy, the concomitant importance of postpartum weight loss has not been given equal attention. A meta-analysis on the effect of diet, exercise, or both for weight reduction in women after childbirth has found that both diet and exercise together and diet alone help women lose weight after childbirth.

Overweight and Obesity

Seventy percent of American adults are overweight (body mass index [BMI] ≥25 kg/m ² ) or obese (BMI ≥30 kg/m ² ). Pregestational weight gain or obesity and excessive gestational weight gain are now well-established independent risk factors for maternal-fetal complications and long-term risks in adult life for the child. The selected risks include increased miscarriage, congenital anomalies, hypertensive disorders, GDM, macrosomia, and delivery complications that include instrumental delivery, shoulder dystocia, emergency CD, PPH, venous thromboembolism, anesthetic complications, and wound infections. In overweight and obese women, the OR for macrosomia is 1.95 (CI, 95% 1.79–2.11) and aOR for CD is 2.04 (95% CI, 1.41–2.95) for an interpregnancy weight retention of two or more BMI units. Being overweight or obese before pregnancy is also associated with a higher risk of fetal loss, and losing 4 kg or more before pregnancy is associated with a lower risk of fetal loss.

Maternal obesity is a potential risk factor for childhood obesity and asthma. The children of women who are overweight or obese during pregnancy are also at increased risk for cognitive deficits, externalizing problems (particularly attention-deficit/hyperactivity disorder), and internalizing psychopathology in childhood and adolescence. These findings should be interpreted with caution due to measurement issues in gestational weight gain and potential confounding effects of shared familial characteristics (i.e., genetics and maternal and child's lifestyle factors).

Emerging evidence supports the role of first microbial contacts in promoting and maintaining a balanced immune response in early life, and recent findings suggest that microbial contact begins prior to birth and is shaped by the maternal microbiota, which is related to maternal BMI. Although the mechanisms remain unclear, postnatal maturation of immune regulation seems to be largely driven by exposure to microbes, and the gastrointestinal tract is the largest source of microbial exposure. Early exposures that impact the intestinal microbiota are associated with the development of childhood diseases that may persist into adulthood such as asthma, allergic disorders (atopic dermatitis, rhinitis), chronic immune-mediated inflammatory diseases, type 1 diabetes, obesity, and eczema. Breast milk samples from obese mothers tend to contain a different and less diverse bacterial microbiota compared with milk from those at a healthy weight. Alterations in the bacterial composition of the mother have been shown to affect the development and function of the gastrointestinal tract of her offspring. Thus prepregnancy strategies to modify the microbiota of future mothers may prove to be a safe and effective target for interventions to decrease the risk of allergic and noncommunicable diseases in future generations.

Underweight

Being underweight before pregnancy, or having insufficient gestational weight gain have been considered individual risk factors for the occurrence of miscarriage, PTB, SGA, and hypertensive disorders . Gestational weight gain below the recommendations is associated with higher risk of SGA (OR, 1.53; 95% CI, 1.44 to1.64) and PTB (OR, 1.70; 95% CI, 1.32–2.20) and no significant difference in CD rates (OR, 0.98; 95% CI, 0.96–1.02). A systematic review and meta-analysis has shown that the birthweight of children of mothers with anorexia nervosa is lower by 0.19 kg compared with children of mothers at a healthy weight. A population study from the same authors has also shown that eating disorders are associated with increased odds of receiving fertility treatment and subsequent twin births. Women with anorexia nervosa were more likely to have an unplanned pregnancy and to have mixed feelings about the unplanned pregnancy.

Pregnancy After Bariatric Surgery

Pregnancy after bariatric surgery appears to effectively reduce the risk of complications such as fetal macrosomia, GDM, and hypertensive disorders of pregnancy (see Chapters 31 and 46 ). A study using the Swedish Medical Birth Register from 2006 through 2011 found 670 women who had previously undergone bariatric surgery. Compared with matched control pregnancies, pregnancy after bariatric surgery is associated with lower risks of gestational diabetes (1.9% vs. 6.8%; OR, 0.25; 95% CI, 0.13–0.47) and large-for-gestational-age infants (8.6% vs. 22.4%; OR, 0.33; 95% CI, 0.24–0.44), higher risk of SGA infants (15.6% vs. 7.6%; OR, 2.20; 95% CI, 1.64–2.95) and shorter gestation (273 vs. 277 days; mean difference −4.5 days; 95% CI, −2.9 to −6.0). A recent systematic review and meta-analysis of 20 cohort studies including 8364 women who had bariatric surgery showed reduced rates of GDM, macrosomia, gestational hypertension, PPH, and CD rates. A group of patients showed an increase in SGA and PTB when compared with control subjects matched for pre-surgery body mass index.

Women who become pregnant after bariatric surgery constitute a unique obstetric population with an increased risk of severe micronutrient deficiencies. As such, screening for micronutrients should be considered in the preconception period or at the first prenatal visit and should include the following: complete blood count, iron, ferritin, folate, calcium, zinc, magnesium, iodine, and vitamins A, B12, D, and K. Additional screening and supplementation should occur every trimester and postpartum. Women should follow Institute of Medicine weight gain recommendations and serial evaluation of fetal growth should be performed to monitor for intrauterine growth restriction (IUGR).

Intimate Partner Violence

Intimate partner violence (IPV)—also called domestic violence, battering, or spouse abuse—is a pervasive problem across women's lifespans. More than one in three women in the US have experienced rape, physical violence, or stalking either in person or electronically through mobile devices and social media. Although IPV cuts across gender, racial, ethnic, and socioeconomic boundaries, racial differences do exist ( Fig. 5.2 ). Data from National Intimate Partner and Sexual Violence Surveys (NISVS) indicate that the prevalence is highest among women who are multiracial (57%) and lowest among women who are of Asian-Pacific Island heritage (18%). Risk factors for being an IPV victim include but are not limited to age (adolescence and young adulthood), low income, low educational attainment, unemployment, and childhood physical or sexual victimization.

Pregnancy and the postpartum period are often when IPV begins. Every year, approximately 324,000 pregnant women are abused in the US. However, the true prevalence of IPV is unknown because many victims are afraid to disclose their personal experiences of violence. The consequences of IPV in pregnancy impact not only the mother but the child as well ( Fig. 5.3 ).

Maternal problems can be categorized into physical and mental. Physical complications include substance abuse, smoking, late entry into prenatal care, and preterm delivery. Poor maternal bonding, depression, anxiety, increased risk for suicide, and being a victim of homicide are some of the negative maternal results. The impacts of IPV on the infant are lifelong and range from LBW to developmental delay, emotional problems, sleep problems, and the potential to perpetrate IPV.

Because prenatal care often provides regular contact with a health care provider, the perinatal period is an ideal “window of opportunity” to address IPV. The US Department of Health and Human Services recommend that IPV screening and counseling should be a core part of women's preventive health visits. Screening for IPV should be done at the first prenatal visit, at least once per trimester, and at the postpartum check. The screening question in pregnancy can be “Since you became pregnant, have you been physically hurt by anyone?” If positive, IPV support and prevention and referral options should be part of the screening. The referral list should include the national 24-hour toll-free hotline. Even if abuse is not acknowledged, normalizing the IPV screening in a caring manner and having educational materials readily accessible is helpful.

Active and Passive Smoking

In many countries, smoking has replaced poverty as the most important risk factor for PTB, IUGR, and sudden infant death syndrome. Cigarette smoke contains scores of toxins that exert a direct effect on placental and fetal cell proliferation and differentiation. The use of or exposure to tobacco products by pregnant women is associated more specifically with placenta previa, placental abruption, placenta accreta, pregnancy bleeding of unknown origin, and preterm premature rupture of membranes. Smoking is linked to a reduction of weight, fat mass, and most anthropometric parameters in the fetus. Epidemiologic studies support a relationship between maternal smoking during pregnancy and adverse neurobehavioral effects for her offspring later in life. The long-term effects of passive and active smoking during pregnancy on childhood or adulthood diseases, including respiratory and cardiovascular disease and cancer, are only starting to emerge from large epidemiologic studies.

In spite of these well-established negative consequences, epidemiologic studies have shown that, depending on the patient population, 20% to 50% of pregnant women smoke or are exposed to passive smoking . In many industrialized countries, prevalence rates of women actively smoking appear to have peaked and have begun to decline, whereas in other countries, smoking is becoming increasingly common among young women. Smoking during pregnancy has been recognized as the most important modifiable risk factor associated with adverse perinatal outcomes. Because most of the placental and fetal damage is done in the first trimester of pregnancy, helping women to quit smoking before conceiving should be a primary objective in prepregnancy counseling or as part of ongoing prenatal care.

Alcohol

Alcohol is a well-established teratogen, and alcohol used during pregnancy can lead to fetal alcohol syndrome (FAS), which includes specific morphologic features such as microcephaly and long-term abnormal neuropsychologic outcomes (see Chapter 8 ). Worldwide, many national departments of health have policy statements that support total alcohol abstinence during pregnancy. Women planning pregnancy should be encouraged to reduce or quit alcohol consumption prior to conceiving. Regular screening for alcohol use should be carried out using such tools as the Tolerance-Annoyance, Cut-Down, Eye-Opener (T-ACE) questionnaire or other simple screening tools, and therapy should be made available to those women who screen positive.

Other Substance Abuse

Substance abuse in pregnancy (see Chapters 8 and 59 ) has increased over the past three decades, and it has been recently estimated that approximately 225,000 infants yearly in the US are exposed prenatally to illicit substances.

Cannabis is the most commonly used illicit substance in the US, predominantly for its pleasurable physical and psychotropic effects. Several states and the District of Columbia have made recreational use of cannabis legal, and this topic has gained national attention. Studies regarding its impact on pregnancy have been conflicting, but it has been shown that after adjustment for coexisting risk factors, cannabis use is associated with increased risk for preterm delivery, can lead to IUGR and withdrawal symptoms in the neonate, has increased risk for neonatal morbidity and mortality, and has been associated with negative effects on intellectual outcome.

Cocaine use in pregnancy can lead to spontaneous abortion, PTB, placental abruption, and preeclampsia. Although fetal cocaine exposure has been linked to numerous abnormalities in arousal, attention, and neurologic and neurophysiologic function, most such effects appear to be self-limited and restricted to early infancy and childhood. Neonatal issues include poor feeding, lethargy, and seizures.

Poor obstetric outcomes can be up to six times higher in patients who abuse opiates such as heroin and methadone. Opiate exposure elicits a well-described withdrawal syndrome that affects central nervous, autonomic, and gastrointestinal systems; this effect is most severe among methadone-exposed infants. Amphetamine use can lead to congenital anomalies and other poor obstetric outcomes. Methamphetamine use in particular is an escalating problem worldwide because it is the only illegal substance that can be made from legally obtained over-the-counter cold medications.

Mothers who use illicit drugs require specialized prenatal care, and the neonate may need extra supportive care. Once recognized, a specialized multidisciplinary approach that includes access to rehabilitation centers can lead to improved maternal and neonatal outcomes.

Mercury Exposure

Data regarding the accumulation of mercury in fish have led to warnings advising pregnant women to avoid or decrease fish consumption; however, the benefits of omega-3 fatty acids found in fish outweigh the risks . Mercury is neurotoxic and has been associated with a dose-dependent impact on neurologic development. Unfortunately, the harms of mercury are counterbalanced by the benefits of omega-3 fatty acids that include decreased LBW and PTB, an increase in visual acuity, and higher performance on developmental tests and higher IQ scores in offspring. It is unclear whether dietary supplements are similarly beneficial because the stability and bioavailability varies and has not been well characterized. The US Environmental Protection Agency and the FDA have attempted to clarify these mixed messages by recommending that reproductive-age women, pregnant women, and children eat a variety of fish two or three times a week. They recommend 8 to 12 oz of fish per week, and albacore tuna should be limited to not more than 6 oz. Pregnant women should specifically avoid eating fish with a high mercury content (king mackerel, shark, swordfish, and tilefish).

Occupational Hazards and Environmental Exposures

Occupational hazards should be identified. If a patient works in a laboratory with chemicals or in agriculture around a lot of pesticides, she should be advised to identify potential reproductive toxins and limit her exposure. This is an active area of research, and several online resources are available for information about potential environmental and occupational teratogens. Patients whose occupations require heavy physical exercise or excess stress should be informed that they may need to decrease such activity later in pregnancy because both have been associated with an increased risk of PTB and reduced fetal growth in observational studies.