The impact of uterine immaturity on obstetrical syndromes during adolescence.

Pregnant nulliparous adolescents are at increased risk, inversely proportional to their age, of major obstetric syndromes, including preeclampsia, fetal growth restriction, and preterm birth. Emerging evidence indicates that biological immaturity of the uterus accounts for the increased incidence of obstetrical disorders in very young mothers, possibly compounded by sociodemographic factors associated with teenage pregnancy. The endometrium in most newborns is intrinsically resistant to progesterone signaling, and the rate of transition to a fully responsive tissue likely determines pregnancy outcome during adolescence. In addition to ontogenetic progesterone resistance, other factors appear important for the transition of the immature uterus to a functional organ, including estrogen-dependent growth and tissue-specific conditioning of uterine natural killer cells, which plays a critical role in vascular adaptation during pregnancy. The perivascular space around the spiral arteries is rich in endometrial mesenchymal stem-like cells, and dynamic changes in this niche are essential to accommodate endovascular trophoblast invasion and deep placentation. Here we evaluate the intrinsic (uterine-specific) mechanisms that predispose adolescent mothers to the great obstetrical syndromes and discuss the convergence of extrinsic risk factors that may be amenable to intervention.

Placental expression of the heme transporter, feline leukemia virus subgroup C receptor, is related to maternal iron status in pregnant adolescents.

Little is known about the expression of heme transporters in human placenta and possible associations between these transporters and maternal or neonatal iron status. To address this area of research, relative protein expression of 2 heme transporters, Feline Leukemia Virus, Subgroup C, Receptor 1 (FLVCR1) and Breast Cancer Resistance Protein (BCRP), was assessed using Western-blot analysis in human placental tissue in relation to maternal/neonatal iron status and placental iron concentration. Placental FLVCR1 (n = 71) and BCRP (n = 83) expression were assessed at term (36.6-41.7 wk gestation) in a cohort of pregnant adolescents (13-18 y of age) at high-risk of iron deficiency. Both FLVCR1 and BCRP were detected in all placental samples assayed. Placental FLVCR1 expression was positively related to placental BCRP expression (n = 69; R(2) = 0.104; P < 0.05). Adolescents that were anemic at delivery had lower placental FLVCR1 expression (n = 49; P < 0.05). Placental FLVCR1 expression was positively associated with placental iron concentration at delivery (n = 61; R(2) = 0.064; P < 0.05). In contrast, placental BCRP expression was not significantly associated with maternal iron status or placental iron content. Both FLVCR1 and BCRP are highly expressed in human placental tissue, but only FLVCR1 was significantly inversely associated with maternal iron status and placental iron concentration. Further analysis is needed to explore potential functional roles of FLVCR1 in human placental iron transport.

Relationship between maternal growth, infant birthweight and nutrient partitioning in teenage pregnancies.

OBJECTIVE: Teenagers are susceptible to delivering small-for-gestational-age (SGA) infants. Previous studies suggest that maternal growth may contribute, as a result of preferential nutrient partitioning to the mother. We investigated the impact of maternal growth on birthweight in pregnant teenagers in the UK, and examined endocrine mediators of nutrient partitioning. DESIGN: A prospective observational multicentre study, About Teenage Eating, conducted between 2004 and 2007. SETTING: Four hospitals in socially-deprived areas of Manchester and London. POPULATION: A total of 500 pregnant adolescents (14-18 years of age) with a singleton pregnancy were recruited at 10-21 weeks of gestation, with follow-up studies on 368 subjects. A cohort of 80 pregnant adults (25-40 years of age) provided a control group for determining growth. METHODS: Skeletal growth, weight gain and skinfold thickness were measured from first to third trimester, together with maternal levels of micronutrients and metabolic hormones: insulin-like growth factor (IGF) system and leptin. Dietary analyses were performed. MAIN OUTCOME MEASURE: SGA birth. RESULTS: Maternal growth was not associated with SGA birth: growing mothers delivered more large-for-gestational-age infants (OR 2.51; P < 0.05). Growers had greater weight gain (P < 0.001), fat accrual (P < 0.001) and red cell folate concentrations (P < 0.01) than non-growers. Maternal IGF-I (P < 0.01) and leptin (P < 0.001) were positively associated with maternal and fetal growth, whereas IGF-I (P < 0.001) was negatively associated. Teenagers that were underweight at booking or with low weight gain were at greater risk of SGA birth. CONCLUSIONS: Maternal growth was not detrimental to fetal growth in this UK population of teenagers. Greater weight gain and higher concentrations of IGF-I in growing teenagers may provide anabolic drive for maternal and fetal growth.

Essential and long-chain polyunsaturated fatty acid status and fatty acid composition of breast milk of lactating adolescents.

The aims of the present study were to evaluate essential fatty acids (EFA) and long-chain PUFA (LCPUFA) status in lactating adolescents and its association with breast milk composition. Healthy nursing adolescents from Rio de Janeiro, Brazil (n 30; 14-19 years; 30-120 d postpartum), exclusively or predominantly breast-feeding, participated in this study. Breast milk and blood samples were collected after overnight fasting. Fatty acid composition of breast milk, erythrocyte membrane (EM) and plasma NEFA were determined by GC. Indices of fatty acid status (mean melting point (MMP); EFA status index; DHA status indices, 22 : 5n-6:22 : 4n-6 and 22 : 6n-3:22 : 5n-6 ratios) were calculated from EM fatty acid composition. Dietary intake of n-3 fatty acids was low when compared with current recommendations for lactating women. MMP was associated with indices of DHA status, some individual fatty acids in EM and years post-menarche and weeks postpartum, suggesting the use of erythrocyte MMP as a possible comprehensive biochemical marker of LCPUFA status in this physiological condition. The DHA status of lactating adolescents and their milk DHA concentrations were similar to the values of Brazilian lactating adults, but lower compared with the values of lactating adults from other countries. Therefore, these lactating adolescents were apparently not disadvantaged, as compared with the Brazilian adults, when EM and breast milk fatty acid composition were considered. In general, PUFA in milk from adolescents presented few associations with their concentrations in plasma NEFA and with maternal status. However, milk DHA was associated with maternal LCPUFA and DHA states.

Zinc and copper metabolism in pregnancy and lactation of adolescent women.

OBJECTIVE: Pregnant and lactating adolescent women are at risk of zinc and copper deficiency but their capacity for metabolic adaptation is poorly known. This study investigated the effect of pregnancy and lactation on zinc and copper metabolism in adolescent women by comparing biochemical indices between groups in different reproductive states. METHODS: Habitual dietary intake and biochemical indices (zinc, copper, alkaline phosphatase, and ceruloplasmin in plasma; zinc [E-Zn], metallothionein [E-MT], and superoxide dismutase [E-SOD] in erythrocytes) and their relation were compared among non-pregnant non-lactating adolescents (NPNLs; n = 26), third-trimester pregnant adolescents (PAs; n = 26), and lactating adolescents up to 3 mo postpartum (LAs; n = 21). RESULTS: Zinc and copper intakes were not different across groups (on average, 8.7 and 1.0 mg/d, respectively). PAs had lower plasma zinc but higher plasma copper, alkaline phosphatase, and ceruloplasmin levels than did LAs and NPNLs (P < 0.05). E-SOD and E-Zn were similar in all groups but E-MT was higher in the PA and LA groups than in the NPNL group (P < 0.05). Correlations between plasma copper and ceruloplasmin and between E-MT and E-Zn were observed in the LA and NPNL groups (r > or = 0.64, P < 0.01) but not in the PA group. In contrast, correlations between plasma alkaline phosphatase and plasma zinc, between E-MT and plasma zinc, and between E-SOD and E-Zn were observed only in the PA group (r > or = 0.46, P < 0.05). CONCLUSION: Zinc and copper biochemical responses to pregnancy and lactation in the adolescent women studied appeared qualitatively similar to those described in previous studies in adult women. However, the significant correlations observed between the activity of zinc-dependent enzymes and plasma (or erythrocyte) zinc suggest that a poor maternal zinc status may limit the metabolic adaptation capacity of these adolescent women especially during pregnancy.

Calcium absorption is significantly higher in adolescents during pregnancy than in the early postpartum period.

BACKGROUND: Early childbearing may limit skeletal consolidation and increase calcium demands in adolescents. OBJECTIVE: The purpose of this study was to characterize calcium absorption in pregnant and lactating adolescents. DESIGN: Fractional calcium absorption was evaluated in 23 adolescents (mean +/- SD age: 16.5 +/- 1.4 y) during the third trimester of pregnancy (34.7 +/- 1.0 wk gestation) and again in 15 of these adolescents 31 +/- 8 d after delivery. Eight adolescents were breastfeeding their infants during the follow-up study. Fractional calcium absorption was determined by using oral ((46)Ca or (44)Ca) and intravenous ((42)Ca) stable calcium isotopes. Total-body and lumbar spine bone mineral density were measured in adolescents during the postpartum period by using dual-energy X-ray absorptiometry. RESULTS: Fractional calcium absorption was significantly greater during pregnancy than at 3-4 wk postpartum [0.526 +/- 0.152 (n = 23) compared with 0.297 +/- 0.108 (n = 15); P < 0.0001]. Lumbar spine z scores measured 19-44 d after delivery (n = 15) were significantly associated with calcium intake during pregnancy (y = -3.53 + 0.107x; R(2) = 0.355, P < 0.02) and were inversely related to fractional calcium absorption during pregnancy (y = 3.489 - 6.66x; R(2) = 0.52, P = 0.002). A total of 33% (5/15) of adolescents had lumbar spine z scores that met the definition of osteopenia (n = 3) or osteoporosis (n = 2) in the early postpartum period. CONCLUSIONS: Calcium absorption in adolescents was significantly higher during the third trimester of pregnancy than in the early postpartum period, and higher calcium intakes during pregnancy appeared to be protective against loss of trabecular bone at the lumbar spine.

Gestational diabetes mellitus and glucose intolerance among Mexican pregnant adolescents.

There is an increasing incidence of type 2 diabetes mellitus (DM) among adolescents (especially females), and the serum glucose concentrations in pregnant women <25 years during a 3-h oral glucose tolerance test (3-h OGTT) seem to be lower than those of pregnant women >25 years. Among 115 Mexican pregnant adolescents (<18 years) we analyzed their serum glucose concentrations during: a) 1-h 50-g glucose challenge test (GCT) performed at 24-28 weeks of gestation (n = 103) or at 29-35 weeks of gestation (n = 12); b) A standard 3-h OGTT performed 3-5 days later. Eight adolescents had an abnormal GCT, three of whom also had an abnormal 3-h OGTT. Sixteen adolescents (13 with previously normal GCT) had an abnormal 3-h OGTT, 15 classified as GGI and one as gestational DM (GDM). Serum glucose concentrations in adolescents with GGI were higher than in adolescents with normal 3-h OGTT: a) at 60 and 120 min during the 3-h OGTT (p < 0.001); and b) when expressed as the area under the glucose curve (p < 0.001). Adolescents with GGI had serum glucose concentrations during the 3-h OGTT similar to adult, non-diabetic pregnant Mexican women. It is suggested that GGI in pregnant adolescents may represent an early sign of a future deterioration in glucose metabolism, leading to a higher risk for GDM in future pregnancies and/or type 2 DM in adulthood. Thus, the current criteria to diagnose GDM in adults may not completely apply to adolescents, especially in ethnic groups with high risk for glucose abnormalities and considering the frequency of multiparous adolescents, especially in developing countries.

The adolescent with an inborn error of metabolism: medical issues and transition to adulthood.

As patients with inborn errors of metabolism survive longer, understanding of potential medical and psychiatric complications adolescence and adulthood has increased. In general, detailed therapeutic guidelines for specific metabolic disorders are not available, and medical management must be tailored to the individual patient. Close interaction between the biochemical genetics clinic staff, primary care physician, mental health professional, and other specialists is necessary to formulate an integrated care plan. The education of the patient and family is a critical function of the biochemical genetics clinic, and transition from dependence on parents or other care providers to full independence is gradual. The ultimate goal is for the patient to have the essential knowledge and motivation required to cope responsibly with dietary and medical therapeutic regimens by adolescence or early adulthood. Specific illustrative inborn errors of metabolism are discussed (aminoacidemias, urea cycle defects, organic acidemias, fatty acid oxidation defects, disorders of carbohydrate metabolism, lysosomal storage disorders) in light of potential problems encountered in adolescence and adulthood, including issues involving pregnancy and long-term medical, psychosocial, and psychiatric complications.

The apparent effect of iron supplementation on serum selenium levels in teenage pregnancy.

Numerous studies have suggested a significant role of selenium in the prevention of gynecological carcinoma. These were epidemiological and prospective in humans and therapeutic in laboratory animals. However, no studies have been reported regarding the normal serum selenium levels during pregnancy. The maternal total blood volume increases 30-50% during the second and third trimesters, resulting in lower measured serum levels for those metabolites, which are not increased significantly during pregnancy. A longitudinal study of the serum selenium levels in teenage pregnancy during the last two trimesters and 3 mo postpartum showed progressive elevation from 49 +/- 7 microg/dL after the 32nd week of pregnancy to 114 +/- 7 microg/dL at term, which was statistically significant (p < or = 0.001). Prenatal supplementation with 18 mg of iron per day prevented this elevation. The results of this study suggest that serum selenium levels in women normally double during pregnancy and this doubling is prevented by the minimal daily supplementation of 18 mg of iron, which may be due to increased absorption of selenium into the erythrocytes and incorporation into the glutathione peroxidase enzyme.

Gravidez na adolescência: estudo epidemiológico no Hospital Evangélico de Curitiba / Pregnancy in adolescents: epidemiologic study in Hospital Evangélico de Curitiba

A incidência de gravidez na adolescência vem aumentando, mostrando uma mudança importante no comportamento sexual dos jovens. Vários säo os fatores que acompanham a adolescente grávida, determinando uma gestaçäo de alto risco. Este estudo tem como objetivo determinar a incidência de gestantes adolescentes que deram a luz no HEC, no ano de 1994, bem como avaliar ac condiçöes dos RN, via de parturiçäo e grau de instruçäo, comparando-se as gestantes adolescentes com as näo adolescentes...

Características nutricionales de la gestante en el Hospital Nacional Dos de Mayo / Nutritional characteristc of pregnant women at the Hospital Nacional Dos de Mayo

Se estudió 259 gestantes correspondientes al I(45), II(88) y III(126) trimestre de embarazo; de los cuales 56 eran adolescentes. La evaluación nutricional se hizo desde el punto de vista antropométrico y bioquímico. Se les tomó las siguientes medidas: peso, talla, perimetro de brazo (PB) y pliegue celular subcutáneo tricipital (PCST); con las dos primeras se calculó el Indice de Quetelet (IQ) y con las dos últimas, el área muscular (AM) y el área grasa (AG). Bioquímicamente se determinó hemoglobina (Hb) y hematócrito (Ht); considerándose anémicas aquellas mujeres por debajo de 11 gr/dl. La mayoria de gestantes tiene un IQ dentro de los rangos normales de la referencia para no gestantes, en el resto de gestantes predominó el sobrepeso y la obesidad de tipo temporal. en los indicadores de depósito los resultados fueron análogos al IQ, pero con predominio en el déficet. El 60 por ciento de las gestantes eran anémicas. 33,65 y 66 por ciento según el trimestre de gestación. El 72 por ciento de la población no consumía ningún suplemento. El 69 por ciento de gestantes del II y II trimestre no recibían ningún suplemento. En conclusión, nuestros resultados indican que el problema de las gestantes es la anemia y en menor medida el sobrepeso y obesidad.

Embarazo en la adolescencia / Pregnancy at youth

El presente trabajo es un estudio de 1994 en el area de Kupini-San Isidro, sobre embarazos en la adolescencia. Los adolescentes no reciben una atencion integral a sus necesidades. Debido a la crisis imperante en el pais los padres se ven forzados a prestar poco apoyo a sus hijos. Por falta de orientacion en sus valores el adolescente se ve confrontando situaciones de depresion y aislamiento, haciendose vulnerable a riesgos como el embarazo. Debido a la reduccion de los recursos asignados a servicios sociales como la educacion y la salud, la atencion del adolescente se encuentra muy restringida. Frente a esta problematica, es destacable la actividad del hospital San Gabriel en los programas del adolescente, que promueve trabajos mancomunados entre padres, establecimientos educativos, clubes de madres y los centros de A.P.S.

The relation of cortisol reactivity and anxiety to perinatal outcome in primiparous adolescents.

The relation of cortisol reactivity and self-report anxiety to perinatal outcomes was examined in a sample of 38 primiparous adolescents. Maternal cortisol and anxiety levels obtained in the first half of pregnancy and in mid-third trimester were found to be related to the gestational age of newborns, with higher levels of cortisol and/or anxiety predicting greater chance of pre- or postmature birth. However, when measured over time, a greater increase in cortisol levels was more predictive of positive perinatal outcomes, such as no meconium in labor. These findings suggest that certain levels of maternal reactivity/anxiety are necessary for positive perinatal outcomes.

Situación de la nutrición de hierro en la embarazada adolescente al inicio de la gestación / Iron nutritional status in pregnant adolescents at the start of gestation

The frequency of anemia and iron nutrition deficiency was assessed in 342 low socioeconomic level pregnant teenagers at entry to prenatal care in 5 outpatient clinics from a South Orient area of Santiago Chile. According to the Center for Disease Control Criteria, 1.2 percent of women had iron deficiency anemia. Iron stores were insufficient (defined by a serum ferritin lower than 20 g/L) in 55 percent for women and depleted (serum ferritin lower than 10 g/L) in 21 percent. Women with more than 14 weeks of gestation had lower packed red cell volumes, hemoglobin, mean corpuscular volumes and ferritin levels that women with less than 14 of gestation. It is concluded that the prevalence of iron deficiency anemia is lower than that predicted for a highly vulnerable group but the high frequency of low iron stores should encourage the use of iron supplementation in these teenagers

Effect of high-sugar intake by low-income pregnant adolescents on infant birth weight.

PURPOSE: The objective of this study was to determine the effect of total sugar intake by pregnant adolescents from low-income families on infant birth weight and small-for-gestational-age (SGA) infants. METHODS: The study sample consisted of 337 adolescents, enrolled in a county-wide demonstration project in Camden, New Jersey, who delivered live, singleton newborns. The adolescents were divided into two groups at the 90th percentile for the study sample total sugar intake (206 g): high-sugar intake (> or = 206 g, n = 34) and low-sugar intake group (< 206 g, n = 303). RESULTS: The sample was 46% black, 30% white, and 24% Hispanic. The sample gestational age and birth weight (mean +/- SD) were 39 +/- 3 weeks and 3189 +/- 666 g, respectively. After adjusting for energy intake, the high- compared with the low-sugar intake group was more likely to consume higher total sugar and carbohydrate but lower protein and fat. Likewise, the high-compared to the low-sugar intake group consumed significantly more calcium and magnesium. After adjusting for possible confounding variables such as maternal age, ethnicity, marital status, parity, smoking, net weight gain, body mass index, energy intake, and gestational age at birth, adolescents on high- compared to low-sugar diets gave birth to infants weighing 215 +/- 104 g less (p = 0.04). The adjusted odds ratios were 3.41 (95% confidence interval, 1.14 to 10.23) for delivering a SGA infant among adolescents with high- compared with low-sugar intakes. CONCLUSIONS: Low-income adolescents consuming high-sugar diets are at increased risk for delivering lower birth weight and SGA infants.

Zinc status of a group of pregnant adolescents at 36 weeks gestation living in southern Ontario.

OBJECTIVE: Pregnant adolescents have very high zinc (Zn) requirements to support the developing fetus and to maintain skeletal maturation after menarche. METHODS: Sixty-six adolescents aged 17.1 +/- 0.15 years (mean +/- SEM; range 14.5-19.0 years) were recruited from three regions of Southern Ontario at 35.9 +/- 0.15 weeks gestation. Data on sociodemographic status, health, infant birth weight and birth length, smoking, alcohol consumption, and prenatal supplement use were collected. Fasting venipuncture blood was analyzed for Zn (via AAS) and alkaline phosphatase in plasma; scalp hair was analyzed for Zn by instrumental neutron activation. RESULTS: Mean (95% CI) values were: plasma Zn 10.7 (10.0-11.5) mumol/L; plasma alkaline phosphatase 46.6 (43.7-49.5) U/L; hair Zn 2.64 (2.52-2.77) mumol/g. None of the plasma and hair Zn values were indicative of suboptimal Zn status. Mean plasma Zn concentrations of subjects (n = 19) consuming a supplement with Zn sulfate were higher than those of subjects consuming a supplement with Zn oxide (n = 18) (12.2 vs 9.7 mumol/L; p < 0.02) and unsupplemented subjects (n = 11) (9.4 mumol/L). Plasma Zn concentrations correlated negatively with reported birth lengths (mean +/- SEM = 51.6 +/- 0.31 cm) while accounting for chronological age (r = 0.42; p < 0.01), but not with reported birth weights (mean +/- SEM = 3.439 +/- 0.107 kg). CONCLUSIONS: Results emphasize that the form of Zn must be taken into account when considering the impact of prenatal supplements containing Zn on plasma Zn concentrations. Suboptimal Zn status was not prevalent in these pregnant adolescents.

Características de las adolescentes obstétricas: estudio comparativo con pacientes de 19 a 30 años del Hospital Universitario de Caldas-1989

Comparamos un grupo de 490 primigestantes primíparas adolescentes, de 18 años de edad o menos, on 471 primigestantes primíparas de 19-30 años. Encontramos dos tipos de diferencias: unas clínica y estadísticaente significativas. Otras sólo clínicamente importantes. En cuanto a las primeras, está la mayor incidencia de unión inestable y de pacientes sin control prenatal entre las adolescentes. La morbilidad gestacional fue mayor entre las adolescentes en unión inestable(p menor 0.05). Hubo también mayor incidencia de amenaza de parto pretérmino (p-0.023) y de sufrimiento fetal (p-0.045) entre las adolescentes que en el subgrupo testigo de 19-24 años. En cuanto a diferencias importantes con significancia clínica no estadística encontramos: mayor incidencia entre las adolescentes, de atonía uterina, sufrimiento fetal intraparto, y parto disfuncional, que en las de 19-24 años y de preeclampsia-eclapmsia , amenaza de parto pretérmino, recién nacido pretérmino, bajo peso para la edad gestacional y RCIU que en el grupo de comparación de 25-30años. La incidencia de preeclampsia-eclampsia en adolescentes primigestantes primíparas fue en nuestro estudio de 9.2 por ciento, 2.2 veces mayor que el promedio de 4.1 por ciento reportado por Pardo-Uriza (2) en su estudio cooperativo de 11 Instituciones Colombianas

Adolescencia y nutrición: determinantes de la evolución del peso en el posparto / Adolescence and nutrition: determinants of weight evolution in postpartum

El objetivo del estudio fue estudiar las determinantes de los cambios en el estado de nutrición (evolución del peso en el puerperio) en un grupo de adolecentes. Se estudiaron en el Instituto Nacional de Perinatología, 28 adolecentes en el posparto (4, 8, 12, 16, 20 y 24 semanas). Se les midió el peso y la talla; además se investigó si establecieron la lactancia y si continuaron estudiando/trabajando o si se quedaron en el hogar en ese periodo. Se encontró que existió una asociación directa y significativa entre la práctica de la lactancia y la pérdida de peso, no encontrándose asociación entre la actividad de la mujer y su cambio de peso, a pesar de encontrarse una tendencia a ganar peso entre las mujeres que estudian o trabajan fuera del hogar. Sin embargo, se encontró una relación entre la actividad de la mujer y el estableciminto de la lactancia, las mujeres que permanecieron en el hogar lactaron, mientras que las que estudiaron o trabajaron fuera de l hogar no lactaron. Con base a lo anterior se integró un modelo de comportamiento.

Bioavailability of iron in prenatal multivitamin/multimineral supplements administered to pregnant teenagers.

Absorption of elemental iron from three single-daily-dose prenatal multivitamin/multimineral supplements was compared in bioavailability studies of subjects under fasting and postprandial conditions. Each of the supplements (Stuartnatal 1 + 1, Stuart Prenatal, and Materna 1.60) contained 60 or 65 mg of iron. The subjects, teenagers in the second trimester of pregnancy, were assigned to the fasting or postprandial conditions at intervals of three to seven days. For the postprandial condition, subjects took the supplement after eating a standardized meal that had been designed to provide a minimal amount of iron and no caffeine (which inhibits iron absorption); blood was drawn at 0, 1, 3, 6, and 8 hours. Bioavailability studies showed that all three supplements provided adequate levels (at least 3.5 mg) of absorbed iron when taken postprandially. The highest quantity of net iron transport as well as the most rapid intestinal transport in either condition was yielded by Stuartnatal 1 + 1 taken in the fasting state. In the postprandial condition, Materna 1.60 demonstrated the fastest transport time and highest net iron transport; when given to a subject in the fasting condition, however, this supplement provided less than the recommended 3.5 mg of absorbed iron. These results suggest that iron absorption is influenced by supplement formulation as well as the presence or absence of food. Considering variations in compliance when iron is to be taken on an empty stomach as well as variable absorption in the fasting state, the most reliable supplementation would appear to be achieved by instructing pregnant women to take multivitamin/multimineral supplements at mealtime.