Michelle F. Mottola

Nutrition and exercise prevent excess weight gain in overweight pregnant women.

PURPOSE To determine the effect of a Nutrition and Exercise Lifestyle Intervention Program (NELIP) for overweight (OW) and obese (OB) pregnant women on pregnancy weight gain, birth weight, and maternal weight retention at 2 months postpartum. METHODS This is a single-arm intervention matched by prepregnant body mass index, age, and parity to a historical cohort (4:1). Women with a prepregnancy body mass index of > or = 25.0 kg x m(-2) (N = 65) participated in a NELIP starting at 16-20 wk of pregnancy, continuing until delivery. NELIP consisted of an individualized nutrition plan with total energy intake of approximately 2000 kcal x d(-1) (8360 kJ x d(-1)) and 40%-55% of total energy intake from carbohydrate. Exercise consisted of a walking program (30% HR reserve), three to four times per week, using a pedometer to count steps. Matched historical cohort (MC; N = 260) was from a large local perinatal database. RESULTS Weight gained by women on the NELIP was 6.8 +/- 4.1 kg (0.38 +/- 0.2 kg x wk(-1)), with a total pregnancy weight gain of 12.0 +/- 5.7 kg. Excessive weight gain occurred before NELIP began at 16 wk of gestation. Eighty percent of the women did not exceed recommended pregnancy weight gain on NELIP. Weight retention at 2 months postpartum was 2.2 +/- 5.6 kg with no difference between the OW and the OB women on NELIP. Mean birth weight was not different between NELIP (3.59 +/- 0.5 kg) and MC (3.56 +/- 0.6 kg, P > 0.05). CONCLUSIONS NELIP reduces the risk of excessive pregnancy weight gain with minimal weight retention at 2 months postpartum in OW and OB women. This intervention may assist OW and OB women in successful weight control after childbirth.

Recent advances in understanding maternal and fetal responses to exercise.

In the past decade, physical health fitness has become increasingly more important in the lives of women of child-bearing age. Many have made regular, and sometimes vigorous commitments to exercise programs. In 1985, the American College of Obstetricians and Gynecologists (ACOG) developed a set of guidelines for women who plan to exercise during pregnancy. Recommendations were based on available, but somewhat limited, scientific data and common sense. Since that time, researchers have learned a significant amount of new information about how a pregnant woman and her fetus respond to aerobic activity. The objective of this communication is to review recent investigations in this area. Specific topics include a) maternal responses to exercise, b) fetal responses to maternal exercise, c) animal research models, and d) pregnancy and physical conditioning. Our objectives are to present information that will a) stimulate new and innovative research designs for exercise and pregnancy studies, and b) add significantly to our knowledge and ability to develop safe and effective exercise programs for women who wish to remain physically active throughout a normal-term pregnancy.

A walking intervention improves capillary glucose control in women with gestational diabetes mellitus: a pilot study

Exercise prescriptions that can be translated into clinical recommendations are clearly needed for women with gestational diabetes mellitus (GDM). A pilot project was developed to document the effectiveness of a structured low-intensity walking protocol on capillary glucose control in GDM women. Ten GDM women followed conventional management of diet and insulin therapy, plus a low-intensity walking program (W) from diagnosis to delivery. Capillary glucose concentrations, insulin requirements, and pregnancy outcomes were compared with a matched cohort by body mass index (BMI), age, and insulin usage (20 GDM women who followed conventional management alone (C)). Baseline capillary glucose concentrations were not significantly different between the W and C groups. The W group had an average acute drop in capillary glucose concentration from pre- to post-exercise of 2.0 mmol x L(-1). In addition, the W group had significantly lower mean glucose concentrations in the fasted state and 1 h after meals than the C group in the week prior to delivery. These lower glucose concentrations were achieved while requiring fewer units of insulin per day (C, 0.50 +/- 0.37 U x kg(-1); W, 0.16 +/- 0.13 U x kg(-1); p < 0.05), injected less frequently. These results suggest an effective role in glucose regulation for this structured walking program.

Guidelines for Physical Activity During Pregnancy Comparisons From Around the World

Introduction. Women attain numerous benefits from physical activity during pregnancy. However, because of physical changes that occur during pregnancy, special precautions are also needed. This review summarizes current guidelines for physical activity among pregnant women worldwide. Methods. We searched PubMed (MedLINE) for country-specific governmental and clinical guidelines on physical activity during pregnancy through the year 2012. We cross-referenced with articles referring to guidelines, with only the most recent included. An abstraction form was used to extract key details and summarize. Results. In total, 11 guidelines were identified from 9 countries (Australia, Canada, Denmark, France, Japan, Norway, Spain, United Kingdom, United States). Most guidelines supported moderate-intensity physical activity during pregnancy (10/11) and indicated specific frequency (9/11) and duration/time (9/11) recommendations. Most guidelines provided advice on initiating an exercise program during pregnancy (10/11). Six guidelines included absolute and relative contraindications to exercise. All guidelines generally ruled-out sports with risks of falls, trauma, or collisions. Six guidelines included indications for stopping exercise during pregnancy. Conclusion. This review contrasted pregnancy-related physical activity guidelines from around the world, and can help inform new guidelines as they are created or updated and facilitate the development of a worldwide guideline.

Exercise Is Associated with a Reduction in Gestational Diabetes Mellitus.

PURPOSE The objective of this study is to assess the effectiveness of a maternal exercise program (land/aquatic activities, both aerobic and muscular conditioning) in preventing gestational diabetes mellitus (GDM). METHODS Three hundred and forty-two pregnant women from Spain (age, 33.24 ± 4.3 yr) without obstetric contraindications were recruited for a clinical randomized controlled trial. The intervention group (IG, n = 101) exercised for 60 and 50 min on land and in water, respectively, three times per week. The control group (n = 156) received usual standard care. RESULTS The prevalence of GDM was reduced in the IG group (IG, 1%, n = 1, vs control group, 8.8%, n = 13 (χ1 = 6.84, P = 0.009)) with a significant risk estimate (odds ratio = 0.103; 95% confidence interval, 0.013-0.803). CONCLUSION The exercise program performed during pregnancy reduced the prevalence of GDM by preserving glucose tolerance.

Development and validation of exercise target heart rate zones for overweight and obese pregnant women

Validated target heart rate (THR) zones for exercise prescription for overweight and obese pregnant women have not been developed. The purposes of this study were to determine if heart rate reserve (HRreserve) is best described by aerobic capacity at peak exercise or by aerobic capacity reserve (VO2 reserve) and to develop and validate THR zones for light-intensity exercise (20%-39%VO2 reserve) in sedentary overweight and obese pregnant women. One hundred six women between 16 and 20 weeks gestation with medical clearance performed a progressive treadmill test to volitional fatigue (peak). Data from every 4th subject were used for cross-validation. Two linear regression equations were performed for each subject, then pooled to obtain mean group values (+/- SD): %HRreserve vs. %VO2 peak and %HRreserve vs. %VO2 reserve. THR zones equivalent to 20%-39%VO2 reserve were developed and validated based on the strongest relationship. %HRreserve had a stronger linear relationship with %VO2 reserve (y = 1.046x -7.561; R2 = 0.741) than %VO2 peak (y = 1.259x -28.795; R2 = 0.604). Validated THR ranges for sedentary overweight and obese pregnant women are 102-124 beats.min-1 (20-29 years of age) and 101-120 beats.min-1 (30-39 years of age), representing an exercise intensity of 20%-39%VO2 reserve as recommended by the American College of Sports Medicine for previously sedentary pregnant women. Overweight and obese women who are medically prescreened can exercise during pregnancy within our validated THR zones. The relationship between HR and VO2 remains strong, but the two are not equivalent in this population group.

Timing of excessive pregnancy-related weight gain and offspring adiposity at birth.

OBJECTIVE: To evaluate whether the timing of excessive maternal weight gain in a cohort of women following current guidelines for healthy living during pregnancy affects neonatal adiposity at birth. METHODS: One hundred seventy-two healthy women who were at least 18 years old with body mass indexes (BMIs) of at least 18.5 were recruited between 16 weeks and 20 weeks of gestation. The cohort followed healthy living guidelines during pregnancy and were retrospectively grouped according to 2009 Institute of Medicine guidelines for weight gain in the first and second halves of pregnancy: 1) appropriate gestational weight gain (ie, within Institute of Medicine recommendations) in the first and second halves of pregnancy (“overall appropriate”); 2) appropriate gestational weight gain in the first half of pregnancy and excessive gestational weight gain in the second half of pregnancy (“late excessive”); 3) excessive gestational weight gain in the first half of pregnancy and appropriate gestational weight gain in the second half of pregnancy (“early excessive”); and 4) excessive gestational weight gain throughout pregnancy (“overall excessive”). Primary measures included neonatal weight, length, BMI, and body fat at birth measured 6–18 hours after delivery. Neonatal body fat greater than 14% was considered excessive. RESULTS: Neonates of women who gained excessively in the first half of pregnancy exhibited greater heel-crown length, birth weight, and excessive body fat (“early excessive” 17.5±3.1%, “overall excessive” 18.7±3.3%) compared with those born to women who gained appropriately (“overall appropriate” 13.2±4.1%; “late excessive” 14.7±3.3%; P<.01). Neonates of women who gained excessively in the first half of pregnancy had an increased risk (odds ratio [OR] 2.64, 95% confidence interval [CI] 1.35–5.17) of elevated body fat at birth compared with neonates of women with total excessive weight gain (OR 1.49, 95% CI 0.80–2.79). CONCLUSION: Timing of excessive weight gain is an important factor influencing neonatal morphometrics. Prevention of early excessive weight gain should be encouraged in the period before conception and reinforced early in pregnancy. LEVEL OF EVIDENCE: II

Exercise in the postpartum period: practical applications.

Pregnancy, birth, and the postpartum period are important events in the reproductive lives of women. Exercise guidelines exist for pregnancy, but recommendations for exercise during the postpartum period are virtually nonexistent. It is important to examine the theoretic concerns and potential benefits of exercise during this period, especially with respect to weight retention following pregnancy, lactation performance, and infant growth. It is recommended to increase the definition of the postpartum period to 1 year, because many physiologic changes due to pregnancy remain up to 1 year after delivery. Evidence-based guidelines are presented for postpartum exercise and lactation. Future research should address the impact of exercise and lactation on bone mineral density, nutrition status and weight loss, cardiovascular health, and how to optimize health promotion during the postpartum period.

The important role of physical activity in the prevention and management of gestational diabetes mellitus.

The actual pathophysiology behind gestational diabetes mellitus (GDM) is still unclear, but a deterioration in insulin resistance beyond that induced by pregnancy, combined with beta cell dysfunction, plays a key role. Interventions that help improve glucose tolerance by attenuating pregnancy‐induced insulin resistance or achieve glycaemic control may therefore help in preventing and managing GDM. In non‐pregnant populations, physical activity has been associated with an improvement in glucose homeostasis and insulin sensitivity and a risk reduction for type 2 diabetes mellitus (T2DM) and is a cornerstone for T2DM treatment. However, there is still controversy regarding the benefits of physical activity in preventing and managing GDM. The objective of this review is therefore to provide a comprehensive overview of the effect of prenatal physical activity–based interventions on (1) glucose tolerance, insulin sensitivity and GDM prevention and (2) glycaemic control and insulin use in GDM women. On the basis of the available literature, there is a lack of consistent evidence regarding the benefits of physical activity on improving glucose tolerance and insulin sensitivity and preventing GDM. However, it appears that physical activity may help to achieve good glycaemic control and limit insulin use in GDM women. Compliance appears to be a major problem in physical activity–based intervention studies aimed at GDM prevention. Rigorous scientific research is still required to make an informed decision about the role of physical activity in the prevention and management of GDM and to develop evidence‐based physical activity guidelines for GDM prevention and management. Copyright

Effect of exercise intensity and duration on capillary glucose responses in pregnant women at low and high risk for gestational diabetes

Exercise may influence glucose metabolism during pregnancy. We examined the effect of exercise intensity and duration on capillary glucose responses in pregnant women at low and high risk for gestational diabetes mellitus (GDM) who followed a modified GDM meal plan.