The effect of the pregnancy-induced hypertension on fetal growth: a review of the literature

Maternal risk factors associated with term low birth weight in India: A review

Low birth weight is one of the leading factors for infant morbidity and mortality. To a large extent affect, various maternal risk factors are associated with pregnancy outcomes by increasing odds of delivering an infant with low birth weight. Despite this association, understanding the maternal risk factors affecting term low birth weight has been a challenging task. To date, limited studies have been conducted in India that exert independent magnitude of these effects on term low birth weight. The aim of this review is to examine the current knowledge of maternal risk factors that contribute to term low birth weight in the Indian population. In order to identify the potentially relevant articles, an extensive literature search was conducted using PubMed, Goggle Scholar and IndMed databases (1993 – Dec 2020). Our results indi­cate that maternal age, educational status, socio-economic status, ethnicity, parity, pre-pregnancy weight, maternal stature, maternal body mass index, obstetric history, maternal anaemia, gestational weight gain, short pregnancy outcome, hypertension during pregnancy, infection, antepartum haemorrhage, tobacco consumption, maternal occupation, maternal psychological stress, alcohol consumption, antenatal care and mid-upper arm circumference have all independent effects on term low birth weight in the Indian pop­ulation. Further, we argue that exploration for various other dimensions of maternal factors and underlying pathways can be useful for a better understanding of how it exerts independent association on term low birth weight in the Indian sub-continent.

Ambient and household PM2.5 pollution and adverse perinatal outcomes: A meta-regression and analysis of attributable global burden for 204 countries and territories

BACKGROUND

Particulate matter <2.5 micrometer (PM2.5) is associated with adverse perinatal outcomes, but the impact on disease burden mediated by this pathway has not previously been included in the Global Burden of Disease (GBD), Mortality, Injuries, and Risk Factors studies. We estimated the global burden of low birth weight (LBW) and preterm birth (PTB) and impacts on reduced birth weight and gestational age (GA), attributable to ambient and household PM2.5 pollution in 2019.

METHODS AND FINDINGS

We searched PubMed, Embase, and Web of Science for peer-reviewed articles in English. Study quality was assessed using 2 tools: (1) Agency for Healthcare Research and Quality checklist; and (2) National Institute of Environmental Health Sciences (NIEHS) risk of bias questions. We conducted a meta-regression (MR) to quantify the risk of PM2.5 on birth weight and GA. The MR, based on a systematic review (SR) of articles published through April 4, 2021, and resulting uncertainty intervals (UIs) accounted for unexplained between-study heterogeneity. Separate nonlinear relationships relating exposure to risk were generated for each outcome and applied in the burden estimation. The MR included 44, 40, and 40 birth weight, LBW, and PTB studies, respectively. Majority of the studies were of retrospective cohort design and primarily from North America, Europe, and Australia. A few recent studies were from China, India, sub-Saharan Africa, and South America. Pooled estimates indicated 22 grams (95% UI: 12, 32) lower birth weight, 11% greater risk of LBW (1.11, 95% UI: 1.07, 1.16), and 12% greater risk of PTB (1.12, 95% UI: 1.06, 1.19), per 10 μg/m3 increment in ambient PM2.5. We estimated a global population-weighted mean lowering of 89 grams (95% UI: 88, 89) of birth weight and 3.4 weeks (95% UI: 3.4, 3.4) of GA in 2019, attributable to total PM2.5. Globally, an estimated 15.6% (95% UI: 15.6, 15.7) of all LBW and 35.7% (95% UI: 35.6, 35.9) of all PTB infants were attributable to total PM2.5, equivalent to 2,761,720 (95% UI: 2,746,713 to 2,776,722) and 5,870,103 (95% UI: 5,848,046 to 5,892,166) infants in 2019, respectively. About one-third of the total PM2.5 burden for LBW and PTB could be attributable to ambient exposure, with household air pollution (HAP) dominating in low-income countries. The findings should be viewed in light of some limitations such as heterogeneity between studies including size, exposure levels, exposure assessment method, and adjustment for confounding. Furthermore, studies did not separate the direct effect of PM2.5 on birth weight from that mediated through GA. As a consequence, the pooled risk estimates in the MR and likewise the global burden may have been underestimated.

CONCLUSIONS

Ambient and household PM2.5 were associated with reduced birth weight and GA, which are, in turn, associated with neonatal and infant mortality, particularly in low- and middle-income countries.

Machine learning improves early prediction of small-for-gestational-age births and reveals nuchal fold thickness as unexpected predictor

OBJECTIVE

To investigate the performance of the machine learning (ML) model in predicting small-for-gestational-age (SGA) at birth, using second-trimester data.

METHODS

Retrospective data of 347 patients, consisting of maternal demographics and ultrasound parameters collected between the 20th and 25th gestational weeks, were studied. ML models were applied to different combinations of the parameters to predict SGA and severe SGA at birth (defined as 10th and third centile birth weight).

RESULTS

Using second-trimester measurements, ML models achieved an accuracy of 70% and 73% in predicting SGA and severe SGA whereas clinical guidelines had accuracies of 64% and 48%. Uterine PI (Ut PI) was found to be an important predictor, corroborating with existing literature, but surprisingly, so was nuchal fold thickness (NF). Logistic regression showed that Ut PI and NF were significant predictors and statistical comparisons showed that these parameters were significantly different in disease. Further, including NF was found to improve ML model performance, and vice versa.

CONCLUSION

ML could potentially improve the prediction of SGA at birth from second-trimester measurements, and demonstrated reduced NF to be an important predictor. Early prediction of SGA allows closer clinical monitoring, which provides an opportunity to discover any underlying diseases associated with SGA.

Impact of Maternal Air Pollution Exposure on Children's Lung Health: An Indian Perspective

Air pollution has become an emerging invisible killer in recent years and is a major cause of morbidity and mortality globally. More than 90% of the world’s children breathe toxic air every day. India is among the top ten most highly polluted countries with an average PM₁₀ level of 134 μg/m³ per year. It is reported that 99% of India’s population encounters air pollution levels that exceed the World Health Organization Air Quality Guideline, advising a PM_2.5 permissible level of 10 μg/m³. Maternal exposure to air pollution has serious health outcomes in offspring because it can affect embryonic phases of development during the gestation period. A fetus is more prone to effects from air pollution during embryonic developmental phases due to resulting oxidative stress as antioxidant mechanisms are lacking at that stage. Any injury during this vulnerable period (embryonic phase) will have a long-term impact on offspring health, both early and later in life. Epidemiological studies have revealed that maternal exposure to air pollution increases the risk of development of airway disease in the offspring due to impaired lung development in utero. In this review, we discuss cellular mechanisms involved in maternal exposure to air pollution and how it can impact airway disease development in offspring. A better understanding of these mechanisms in the context of maternal exposure to air pollution can offer a new avenue to prevent the development of airway disease in offspring.

Study on the influence of pregnancy-induced hypertension on neonatal birth weight

To explore the effect of pregnancy-induced hypertension (PIH) on neonatal birth weight and provide the necessary reference value for the maternal and children health service. A cross-sectional study was carried out in Shaanxi Province of China in 2013. And a total of 28 045 singleton live infants and their mothers were recruited using a stratified, multistage, probability-proportional-to-size sampling method. Among the 28 045 women of childbearing age surveyed, multiple linear regression and quantile regression analysis all showed that the birth weight of newborns whose mothers had suffered from PIH during pregnancy was significantly lower than those whose mothers had not suffered from PIH during pregnancy from very low to higher birth weight percentiles (q=0-0.85), an average decrease of 137.45 g (β=-137.45, t=-5.77 and p<0.001). When birth weight was at q=0.90-1.00 percentiles, there was no birth weight difference between two groups. The present cross-sectional study indicated that PIH had an effect of on neonatal birth weight. When pregnant women with PIH are identified then the healthcare professional initiates a closer supervision of their pregnancy in order to ameliorate the status of BP and provide a good intrauterine environment for the fetus. In addition, the gynecologists should admonish the pregnant women that their health is related to the health of their fetus, then gravidas may be more engaged to alert their physician and accept early or preventative interventions. And the healthcare professional should ask and be alert to the issues of hypertension during pregnancy.

Maternal cumulative exposure to extremely low frequency electromagnetic fields and pregnancy outcomes in the Elfe cohort

OBJECTIVES

To study the relations between maternal cumulative exposure to extremely low frequency electromagnetic fields (ELF EMF) and the risk of moderate prematurity and small for gestational age within the Elfe cohort.

METHODS

The Elfe study included 18,329 infants born at 33weeks of gestation or more in France in 2011 and was designed to follow the children until 20years of age. Gestational age and anthropometric data at birth were collected in medical records and small for gestational age was defined according to a French customized growth standard. During interviews, mothers were asked to report their job status during pregnancy. If employed, their occupation was coded according to the International Standard Classification of Occupations 1988 and the date on which they stopped their work was recorded. Cumulative exposure to ELF EMF during pregnancy was assessed, for both mothers who worked and those who did not during pregnancy, using a recently-updated job-exposure matrix (JEM). Cumulative exposure was considered as a categorical variable (<17.5, 17.5-23.8, 23.8-36.2, 36.2-61.6 or ≥61.6μT-days), a binary variable (<44.1 and ≥44.1μT-days) and a continuous variable. Associations were analyzed by logistic regression, adjusting for the mother's lifestyle factors, sociodemographic characteristics and some mother's medical history during and before pregnancy. Analyses were restricted to single births and to complete values for the pregnancy outcomes (n=16,733).

RESULTS

Cumulative exposure was obtained for 96.0% of the mothers. Among them, 37.5% were classified in the 23.8-36.2μT-days category, but high exposures were rare: 1.3% in the ≥61.6μT-days category and 5.5% in the ≥44.1μT-days category. No significant association was observed between maternal cumulative exposure and moderate prematurity and small for gestational age in this exposure range.

CONCLUSION

This large population-based study does not suggest that maternal exposure to ELF EMF during pregnancy is highly associated with risks of moderate prematurity or small for gestational age.

Correlation between maternal anxiety, reactivity of fetal cerebral circulation to auditory stimulation, and birth outcome in normotensive and gestational hypertensive women

This study investigated the correlation between maternal anxiety and blood flow changes through the fetal middle cerebral artery (MCA) after defined acoustic stimulation in 43 normotensive (C) and 40 gestational hypertensive (GH) subjects. Neonatal outcomes (gestational age at birth, Apgar score, birth weight) in the C and GH groups were analyzed. State (STAI-S) and trait (STAI-T) anxiety was assessed using Spielberger's questionnaire. The MCA blood flow was assessed once between 28 and 41 weeks of gestation using color Doppler ultrasound before and after application of defined acoustic stimulus. Relative size of the Pulsatility index (Pi) change (RePi) was calculated. The general hypotheses were: (1) women in GH group would have higher anxiety; (2) higher anxiety correlates with higher RePi change and poorer neonatal outcome; (3) fetuses from the GH group would have poorer neonatal outcome. Subjects from the GH group had higher STAI-T and RePi compared to the C group. A positive correlation between RePi and STAI-S, STAI-T, and systolic/diastolic blood pressure was found in both groups. There were more preterm deliveries in the GH group compared to the C group. A significant effect of STAI-T on body weight was observed in the C and GH group. There was a predictive effect of STAI-T and RePi on the C group, and STAI-S, STAI-T, diastolic blood pressure, and RePi on the GH group in terms of neonatal body weight. This study demonstrates an association between antenatal anxiety in GH women and increased fetal cerebral circulation in response to defined auditory stimulation.

HLA gene expression is altered in whole blood and placenta from women who later developed preeclampsia

Preeclampsia is a multisystem disease that significantly contributes to maternal and fetal morbidity and mortality. In this study, we used a non-biased microarray approach to identify dysregulated genes in maternal whole blood samples which may be associated with the development of preeclampsia. Whole blood samples were obtained at 28 wk of gestation from 5 women who later developed preeclampsia (cases) and 10 matched women with normotensive pregnancies (controls). Placenta samples were obtained from an independent cohort of 19 women with preeclampsia matched with 19 women with normotensive pregnancies. We studied gene expression profiles using Illumina microarray in blood and validated changes in gene expression in whole blood and placenta tissue by qPCR. We found a transcriptional profile differentiating cases from controls; 336 genes were significantly dysregulated in blood from women who developed preeclampsia. Functional annotation of microarray results indicated that most of the genes found to be dysregulated were involved in inflammatory pathways. While general trends were preserved, only HLA-A was validated in whole blood samples from cases using qPCR (2.30- ± 0.9-fold change) whereas in placental tissue HLA-DRB1 expression was found to be significantly increased in samples from women with preeclampsia (5.88- ± 2.24-fold change). We have identified that HLA-A is upregulated in the circulation of women who went on to develop preeclampsia. In placenta of women with preeclampsia we identified that HLA-DRB1 is upregulated. Our data provide further evidence for involvement of the HLA gene family in the pathogenesis of preeclampsia.

Neonatal outcome in hypertensive disorders of pregnancy

BACKGROUND

Hypertensive disorders in pregnancy account for increased perinatal morbidity and mortality when compared to uneventful gestations.

AIMS

To analyze perinatal outcome of pregnancies complicated by different kinds of hypertension to uncomplicated pregnancies in a series of Italian women and to compare our data with series from other countries.

STUDY DESIGN

The sample was divided into four groups of hypertensive women: chronic hypertension (CH), gestational hypertension (GH), preeclampsia (PE), and chronic hypertension complicated by preeclampsia (CHPE). One thousand normal pregnancies served as controls.

SUBJECTS

Neonatal features of the offspring of 965 Italian women with hypertension in pregnancy were evaluated.

MEASURES

Gestational age, birthweight and the rate of small for gestational age were the outcomes. Perinatal asphyxia and mortality were also assessed.

RESULTS

Gestational age, the mean of birth weight and birth percentile were significantly lower in all groups with hypertensive complications when compared with controls. The rate of very early preterm delivery (<32 weeks) was 7.8% in CH, 5.9% in GH, 21.2% in PE and 37.2% in CHPE while it was to 1.2% in the control group. The rate of SGA was globally 16.2% in CH, 22.8% in GH, 50.7% in PE, 37.2% in CHPE and 5% in controls. The rate of SGA in PE was much higher than reported in series from other countries.

CONCLUSION

Comparing our data with those reported from other countries, it is evident that the rate of fetal growth restriction in PE we found in our center, is significantly higher even in the presence of a global lower incidence of PE.

Control of hypertension in pregnancy

The hypertensive disorders of pregnancy are a leading cause of maternal mortality and morbidity. Complications are not limited to preeclampsia but also complicate both preexisting hypertension and isolated gestational hypertension. Blood pressure (BP) management is important but is only one aspect of management of the hypertensive disorders of pregnancy, which may be caused or exacerbated by underlying uteroplacental mismatch between maternal supply and fetal demand. BP treatment thresholds and goals vary in international guidelines, largely reflecting differences in opinion rather than differences in published data. Because of short-term maternal risks, there is consensus that BP should be treated when sustained at greater than or equal to 160 to 170 mm Hg systolic and/or 110 mm Hg diastolic. There is no consensus regarding management of nonsevere hypertension, and randomized controlled trials involving just over 3000 women have not clarified the relative maternal and perinatal risks and benefits. Although antihypertensive therapy may decrease transient severe maternal hypertension, therapy may also impair fetal growth and perinatal health and outcomes. The CHIPS Trial (Control of Hypertension In Pregnancy Study) is recruiting to answer this question.

Exposures to airborne particulate matter and adverse perinatal outcomes: a biologically plausible mechanistic framework for exploring potential

This article has three objectives: to describe the biologically plausible mechanistic pathways by which exposure to particulate matter (PM) may lead to adverse perinatal outcomes of low birth weight (LBW), intrauterine growth retardation (IUGR), and preterm delivery (PTD); review evidence showing that nutrition affects biologic pathways; and explain mechanisms by which nutrition may modify the impact of PM exposure on perinatal outcomes. We propose an interdisciplinary framework that brings together maternal and infant nutrition, air pollution exposure assessment, and cardiopulmonary and perinatal epidemiology. Five possible biologic mechanisms have been put forth in the emerging environmental sciences literature and provide corollaries for the proposed framework. The literature indicates that the effects of PM on LBW, PTD, and IUGR may manifest through the cardiovascular mechanisms of oxidative stress, inflammation, coagulation, endothelial function, and hemodynamic responses. PM exposure studies relating mechanistic pathways to perinatal outcomes should consider the likelihood that biologic responses and adverse birth outcomes may be derived from both PM and non-PM sources. We present strategies for empirically testing the proposed model and developing future research efforts.

Exposures to airborne particulate matter and adverse perinatal outcomes: a biologically plausible mechanistic framework for exploring potential effect modification by nutrition

OBJECTIVES

The specific objectives are threefold: to describe the biologically plausible mechanistic pathways by which exposure to particulate matter (PM) may lead to the adverse perinatal outcomes of low birth weight (LBW), intrauterine growth retardation (IUGR), and preterm delivery (PTD); review the evidence showing that nutrition affects the biologic pathways; and explain the mechanisms by which nutrition may modify the impact of PM exposure on perinatal outcomes.

METHODS

We propose an interdisciplinary conceptual framework that brings together maternal and infant nutrition, air pollution exposure assessment, and cardiopulmonary and perinatal epidemiology. Five possible albeit not exclusive biologic mechanisms have been put forth in the emerging environmental sciences literature and provide corollaries for the proposed framework.

CONCLUSIONS

Protecting the environmental health of mothers and infants remains a top global priority. The existing literature indicates that the effects of PM on LBW, PTD, and IUGR may manifest through the cardiovascular mechanisms of oxidative stress, inflammation, coagulation, endothelial function, and hemodynamic responses. PM exposure studies relating mechanistic pathways to perinatal outcomes should consider the likelihood that biologic responses and adverse birth outcomes may be derived from both PM and non-PM sources (e.g., nutrition). In the concluding section, we present strategies for empirically testing the proposed model and developing future research efforts.

The safety of antihypertensives for treatment of pregnancy hypertension

This review addresses the maternal and perinatal benefits and risks of antihypertensive therapy in pregnancy. It covers the diagnosis of hypertension in pregnancy (with a brief discussion of ambulatory blood pressure measurement) followed by both the general principles of management of pregnancy hypertension and the specifics of individual antihypertensive drugs and drug classes. Discussion is focused on quantitative overviews of randomised, controlled trials, although observational literature is also discussed, particularly in reference to the potential teratogenicity of agents and the safety of their administration to nursing mothers. The treatment of severe hypertension is addressed separately from the treatment of mild-to-moderate hypertension, for which the maternal and fetal risks are substantially different.

Serious perinatal complications of non-proteinuric hypertension: an international, multicentre, retrospective cohort study

OBJECTIVE

To determine the proportion of births complicated by either a pre-existing or a gestational non-proteinuric hypertension, presenting at <34 weeks' gestation, and the associated incidence with 1 or more serious perinatal complications or birth weight <3rd centile for gestational age.

METHODS

A retrospective chart review was conducted in 5 international centres, from 1998 to 2002, where "tight" control (normalization) of blood pressure (BP) is the norm. International Classification of Diseases (ICD) codes were used to identify women who delivered at > or =20 weeks' gestation, with any hypertensive disorder of pregnancy. Women were included if they had a diastolic blood pressure (dBP) of 90 to 109 mm Hg, due to either a pre-existing or a gestational non-proteinuric hypertension, presenting at <34 weeks' gestation. Women were excluded if they had ongoing severe hypertension, or if at presentation with dBP of 90 to 109 mm Hg, they had 1 or more of the following: proteinuria, an indication for "tight" control of BP or imminent delivery, or a known intrauterine fetal death or lethal fetal anomaly. Data were collected on paper forms, scanned into an electronic database, and summarized descriptively by type of hypertension.

RESULTS

There were 305 eligible women (0.7% deliveries, 12.8% hypertensive deliveries) identified with non-proteinuric hypertension that was either pre-existing (133 [43.6%]) or gestational (172 [56.4%]). Regardless of hypertension type, 16.4% (n = 50) of pregnancies were complicated by birth weight <3rd centile or 1 or more serious perinatal complications, 34.3% (n = 100) by preterm birth, 30.8% (n = 94) by preeclampsia, and 2.0% (n = 6) by serious maternal complications.

CONCLUSION

Non-proteinuric pre-existing or gestational hypertension, presenting before 34 weeks' gestation, identifies a subpopulation of hypertensive pregnant women at both substantial perinatal risk and maternal risk. The CHIPS (Control of Hypertension In Pregnancy Study) trial is designed to determine how best to manage the hypertension of such women in order to optimize perinatal outcome.

Drugs in pregnancy. Antihypertensives

Fifty per cent of pregnancies are unplanned, and 1-6% of young women have pre-existing hypertension. However, no commonly used antihypertensive agent is known to be teratogenic. ACE inhibitors (and angiotensin-receptor antagonists) should be discontinued due to fetotoxicity. Five to 10% of pregnant women have hypertension, of which pre-existing hypertension is but one type. There is consensus that severe maternal hypertension (blood pressure >or=170/110 mmHg) should be treated to minimize the risk of acute cerebrovascular complications. Parenteral hydralazine may be associated with a higher risk of maternal hypotension, and intravenous labetalol with neonatal bradycardia. There is no consensus that mild-to-moderate hypertension in pregnancy should be treated. Clinical trials indicate that transient severe hypertension, antenatal hospitalization, proteinuria at delivery and neonatal respiratory distress syndrome may be decreased by normalizing blood pressure, but intrauterine fetal growth restriction may be increased. Methodological problems with published trials warrant cautious interpretation of these findings. Methyldopa and beta-blockers have been used most extensively, although atenolol may impair fetal growth in particular and should be avoided.

Treating hypertension in women of child-bearing age and during pregnancy

Hypertension is found among 1 to 6% of young women. Treatment aims to decrease cardiovascular risk, the magnitude of which is less dependent on the absolute level of blood pressure (BP) than on associated cardiovascular risk factors, hypertension-related target organ damage and/or concomitant disease. Lifestyle modifications are recommended for all hypertensive individuals. The threshold of BP at which antihypertensive therapy should be initiated is based on absolute cardiovascular risk. Most young women are at low risk and not in need of antihypertensive therapy. All antihypertensive agents appear to be equally efficacious; choice depends on personal preference, social circumstances and an agent's effect on cardiovascular risk factors, target organ damage and/or concomitant disease. Although most agents are appropriate for, and tolerated well by, young women, another consideration remains that of pregnancy, 50% of which are unplanned. A clinician must be aware of a woman's method of contraception and the potential of an antihypertensive agent to cause birth defects following inadvertent exposure in early pregnancy. Conversely, if an oral contraceptive is effective and well tolerated, but the woman's BP becomes mildly elevated, continuing the contraceptive and initiating antihypertensive treatment may not be contraindicated, especially if the ability to plan pregnancy is important (e.g. in type 1 diabetes mellitus). No commonly used antihypertensive is known to be teratogenic, although ACE inhibitors and angiotensin receptor antagonists should be discontinued, and any antihypertensive drugs should be continued in pregnancy only if anticipated benefits outweigh potential reproductive risk(s). The hypertensive disorders of pregnancy complicate 5 to 10% of pregnancies and are a leading cause of maternal and perinatal mortality and morbidity. Treatment aims to improve pregnancy outcome. There is consensus that severe maternal hypertension (systolic BP > or = 170mm Hg and/or diastolic BP > or = 110mm Hg) should be treated immediately to avoid maternal stroke, death and, possibly, eclampsia. Parenteral hydralazine may be associated with a higher risk of maternal hypotension, and intravenous labetalol with neonatal bradycardia. There is no consensus as to whether mild-to-moderate hypertension in pregnancy should be treated: the risks of transient severe hypertension, antenatal hospitalisation, proteinuria at delivery and neonatal respiratory distress syndrome may be decreased by therapy, but intrauterine fetal growth may also be impaired, particularly by atenolol. Methyldopa and other beta-blockers have been used most extensively. Reporting bias and the uncertainty of outcomes as defined warrant cautious interpretation of these findings and preclude treatment recommendations.

Perinatal correlates and neonatal outcomes of small for gestational age infants born at term gestation

OBJECTIVE

We sought to examine the current perinatal correlates and neonatal morbidity associated with intrauterine growth failure among neonates born at term gestation.

STUDY DESIGN

We compared 372 small for gestational age (SGA, birth weight <10th percentile) infants born at term gestation to 372 appropriate for gestational age controls (AGA, birth weight 10th to 90th percentile) matched by sex, race, and gestational age within 2 weeks.

RESULTS

Compared with AGA controls, significant (P < .05) maternal risk factors for SGA status included single marital status (59% versus 53%), lower prepregnancy weight (144 +/- 41 lbs versus 153 +/- 40 lbs), lower weight gain during pregnancy (29 +/- 15 lbs versus 33 +/- 15 lbs), smoking (25% versus 17%), hypertension (14% versus 7%), and multiple gestation (9% versus 2%). Mothers of SGA infants were more likely to undergo multiple (>or=3) antenatal ultrasound evaluations (19% versus 7%), biophysical profile monitoring (11% versus 4%), and oxytocin delivery induction (28% versus 16%) (P < .05). Pediatrician attendance was more common among SGA deliveries (50% versus 37%, P < .05). SGA infants had significantly higher rates of hypothermia (18% versus 6%) and symptomatic hypoglycemia (5% versus 1%). These neonatal problems remained significant even when medical or pathologic causes of intrauterine growth failure, including pregnancy hypertension, multiple gestation, and congenital malformations, were excluded.

CONCLUSION

Despite higher rates of pregnancy complications among mothers of SGA infants, the rates of neonatal adverse outcomes are low. However, SGA infants remain at risk for hypothermia and hypoglycemia and require careful neonatal surveillance.

Birth weight and 24-hour ambulatory blood pressure in nonproteinuric hypertensive pregnancy

OBJECTIVE

The aim of this study was to examine the relationship between maternal ambulatory blood pressure monitor measurements during pregnancy and birth weight in a population of women considered to have hypertension according to conventional antenatal clinic measurement.

STUDY DESIGN

A prospective observational study was carried out within the obstetric departments of Leicester Royal Infirmary and Queen Charlotte's Hospital. A total of 237 women were found to have hypertension (blood pressure >/=140/90 mm Hg) without significant proteinuria during examination in the antenatal assessment area. Sequential-day unit blood pressure recordings and a 24-hour automated ambulatory blood pressure recording were performed, and the results were compared with the principal outcome measure of birth weight.

RESULTS

A significant inverse association (gradient, -13.5; 95% confidence interval -23.4 to -3.6) was found between daytime ambulatory diastolic blood pressure measurement and birth weight. An increase of 5 mm Hg in daytime mean diastolic blood pressure was associated with a fall in birth weight of 68.5 g. This association remained after adjustment for potential confounders that included maternal age, maternal weight, smoking status, ethnicity, and gestational age at delivery. No such association was found between obstetric day unit assessment of blood pressure and birth weight.

CONCLUSION

There is a significant association between blood pressure and birth weight in nonproteinuric hypertensive pregnancies. The best predictor of this association is the daytime mean ambulatory diastolic blood pressure measurement. This is further evidence that maternal blood pressure may be an important confounding and potentially genetic variable in the association between birth weight and subsequent adult hypertension.

Association of preeclampsia with high birth weight for age

OBJECTIVE

The purpose of this study was to examine the effect of gestational hypertension and preeclampsia on fetal growth.

STUDY DESIGN

A retrospective cohort study was conducted on the basis of 97,270 pregnancies delivered between 1991 and 1996 in 35 hospitals in northern and central Alberta, Canada. Univariate and multivariate logistic analyses were performed to examine the impact of preeclampsia and gestational hypertension on high-birth-weight (> or =4200 g), large-for-gestational-age, low-birth-weight (<2500 g), and small-for-gestational-age babies.

RESULTS

The rate of high-birth-weight fetuses in women with gestational hypertension (7. 3%) was higher than in those with normal blood pressure (5.6%). After we controlled for confounders, the adjusted odds ratio of high birth weight was 1.44 (95% confidence interval, 1.21-1.70) in women with gestational hypertension. Preeclampsia was also associated with a statistically nonsignificant (P =.054) increased risk of high birth weight (adjusted odds ratio, 1.40; 95% confidence interval 0. 99-1.98). The rate of large-for-gestational-age babies was significantly higher in women with gestational hypertension (4.5%) and preeclampsia (4.7%) than in those with normal blood pressure (2. 2%), with adjusted odds ratios of 1.50 (95% confidence interval, 1. 22-1.85) for gestational hypertension and 1.87 (95% confidence interval, 1.31-2.67) for preeclampsia. Concurrently, women who had gestational hypertension were also at higher risk of having low-birth-weight (adjusted odds ratio, 2.4; 95% confidence interval, 2.13-2.93) and small-for-gestational-age (adjusted odds ratio, 2.04; 95% confidence interval, 1.68-2.48) babies. Women with preeclampsia were also at markedly higher risk of having low-birth-weight (adjusted odds ratio, 4.14; 95% confidence interval, 3.32-5.15) and small-for-gestational-age (adjusted odds ratio, 2.56; 95% confidence interval, 1.92-3.41) babies.

CONCLUSIONS

There is a significant association of preeclampsia and gestational hypertension with large-for-gestational-age infants, in addition to a significant association with low-birth-weight and small-for-gestational-age infants. This study challenges the currently held belief that reduced uteroplacental perfusion is the unique pathophysiologic process in preeclampsia.

Maternal infection, fetal inflammatory response, and brain damage in very low birth weight infants. Developmental Epidemiology Network Investigators

Echolucent images (EL) of cerebral white matter, seen on cranial ultrasonographic scans of very low birth weight newborns, predict motor and cognitive limitations. We tested the hypothesis that markers of maternal and feto-placental infection were associated with risks of both early (diagnosed at a median age of 7 d) and late (median age = 21 d) EL in a multi-center cohort of 1078 infants <1500 x g. Maternal infection was indicated by fever, leukocytosis, and receipt of antibiotic; fetoplacental inflammation was indicated by the presence of fetal vasculitis (i.e. of the placental chorionic plate or the umbilical cord). The effect of membrane inflammation was also assessed. All analyses were performed separately in infants born within 1 h of membrane rupture (n = 537), or after a longer interval (n = 541), to determine whether infection markers have different effects in infants who are unlikely to have experienced ascending amniotic sac infection as a consequence of membrane rupture. Placental membrane inflammation by itself was not associated with risk of EL at any time. The risks of both early and late EL were substantially increased in infants with fetal vasculitis, but the association with early EL was found only in infants born > or =1 after membrane rupture and who had membrane inflammation (adjusted OR not calculable), whereas the association of fetal vasculitis with late EL was seen only in infants born <1 h after membrane rupture (OR = 10.8; p = 0.05). Maternal receipt of antibiotic in the 24 h just before delivery was associated with late EL only if delivery occurred <1 h after membrane rupture (OR = 6.9; p = 0.01). Indicators of maternal infection and of a fetal inflammatory response are strongly and independently associated with EL, particularly late EL.

Impact of pregnancy-induced hypertension on fetal growth

OBJECTIVE

The purpose of this study was to evaluate the effect of different types of pregnancy-induced hypertension on fetal growth.

STUDY DESIGN

A retrospective cohort study was conducted on the basis of 16,936 births from January 1, 1989, through December 31, 1990, by means of data from a population-based perinatal database in Suzhou, China. Pregnancy-induced hypertension was classified as gestational hypertension, preeclampsia, or severe preeclampsia-eclampsia. Univariate and multivariate regression analyses were performed to examine the effect of the various types of pregnancy-induced hypertension on gestational age, preterm birth, birth weight, low birth weight, and intrauterine growth restriction.

RESULTS

Gestation was 0.6 week shorter in women with severe preeclampsia than in normotensive women (P <.01). However, the risk of preterm birth was not increased with any classification of pregnancy-induced hypertension (for severe preeclampsia: adjusted odds ratio 1.75; 95% confidence interval, 0.88-3.47). After adjustment for duration of gestation and other confounders, preeclampsia and severe preeclampsia increased the risk of intrauterine growth restriction and low birth weight. The adjusted odds ratios of low birth weight were 2.65 (1.73-4.39) for preeclampsia and 2.53 (1.19-4.93) for severe preeclampsia. However, the risk of low birth weight was not increased significantly for gestational hypertension (adjusted odds ratio 1.56 [1.00-2.41]).

CONCLUSION

Preeclampsia increases the risk of intrauterine growth restriction and low birth weight.

Annual summary of vital statistics-1997

Many positive trends in the health of Americans continued into 1997. In 1997, the preliminary birth rate declined slightly to 14.6 births per 1000 population, and the fertility rate, births per 1000 women 15 to 44 years of age, was unchanged from the previous year (65.3). These indicators suggest that the downward trend in births observed since the early 1990s may have abated. Fertility rates for white, black, and Native American women were essentially unchanged between 1996 and 1997. Fertility among Hispanic women declined 2% in 1997 to 103.1, the lowest level reported since national data for this group have been available. For the sixth consecutive year, birth rates dropped for teens. Birth rates for women 30 years or older continued to increase. The proportion of births to unmarried women (32.4%) was unchanged in 1997. The trend toward earlier utilization of prenatal care continued for 1997; 82.5% of women began prenatal care in the first trimester. There was no change in the percentage with late (third trimester) or no care in 1997. The cesarean delivery rate rose slightly to 20.8% in 1997, a reversal of the downward trend observed since 1989. The percentage of low birth weight (LBW) infants rose again in 1997 to 7.5%. The percentage of very low birth weight was up only slightly to 1.41%. Among births to white mothers, LBW increased for the fifth consecutive year, to 6.5%, whereas the rate for black mothers remained unchanged at 13%. Much, but not all, of the rise in LBW for white mothers during the 1990s can be attributed to an increase in multiple births. In 1996, the multiple birth rate rose again by 5%, and the higher-order multiple birth rate climbed by 20%. Infant mortality reached an all time low level of 7.1 deaths per 1000 births, based on preliminary 1997 data. Both neonatal and postneonatal mortality rates declined. In 1996, 64% of all infant deaths occurred to the 7.4% of infants born at LBW. Infant mortality rates continue to be more than two times greater for black than for white infants. Among all the states in 1996, Maine, Massachusetts, and New Hampshire had the lowest infant mortality rates. Despite declines in infant mortality, the United States continues to rank poorly in international comparisons of infant mortality. Expectation of life at birth reached a new high in 1997 of 76.5 years for all gender and race groups combined. Age-adjusted death rates declined in 1997 for diseases of the heart, accidents and adverse affects (unintentional injuries), homicide, suicide, malignant neoplasms, cerebrovascular disease, chronic liver disease and cirrhosis, and diabetes. In 1997, mortality due to HIV infection declined by 47%. Death rates for children from all major causes declined again in 1997. Motor vehicle traffic injuries and firearm injuries were the two major causes of traumatic death. A large proportion of childhood deaths continue to occur as a result of preventable injuries.

Ambulatory blood pressure in pregnancy and fetal growth

BACKGROUND

Retarded growth in utero has been linked with high blood pressure and other risk factors for cardiovascular disease in adult life. However, the influence on fetal growth of the maternal blood pressure during pregnancy is not well defined. In a prospective study, we examined the relation between maternal ambulatory blood pressure during pregnancy and indices of fetal growth.

METHODS

We studied 209 healthy nulliparous pregnant women referred to an inner-city district general hospital (86% of 244 consecutively referred women who met the study criteria). 24 h ambulatory blood-pressure recordings were obtained in early (median 18 weeks [IQR 17-18]) mid (28 weeks [28]), and late (36 weeks [36]) gestation. Eight infants delivered before 32 weeks' gestation were excluded from the analysis.

FINDINGS

A 5 mm Hg (1 SD) increase in mean 24 h diastolic blood pressure at 28 weeks' gestation was associated with a 68 g (95% Cl 3-132) decrease in birthweight; a similar change in diastolic pressure at 36 weeks' gestation was associated with a 76 g (24-129) decrease in birthweight. These associations were independent of potential confounders (maternal age, height, weight, cigarette smoking, alcohol intake, ethnic origin, pregnancy hypertension syndromes, and preterm birth). Maternal mean 24 h diastolic blood pressure at 28 weeks' gestation was also inversely associated with the infant's ponderal index at birth in multivariate analysis (p = 0.06). Higher maternal ambulatory blood pressure at 28 weeks' and 36 weeks' gestation also predicted lower head circumference, although these associations were dependent on birthweight. Associations between ambulatory systolic blood pressure and indices of fetal growth were weak and inconsistent and ambulatory blood pressure at 18 weeks' gestation did not predict fetal growth.

INTERPRETATION

There is a continuous inverse association between fetal growth and maternal blood pressure, throughout the range seen in normal pregnancy. Maternal blood pressure may be an important confounding factor in the reported associations between fetal growth retardation and adult hypertension and cardiovascular disease.