Exposure to video display terminals and risk of spontaneous abortion

Clusters of spontaneous abortion among video display terminal (VDT) users in North America and Canada in the late 1970s aroused suspicion about the potential risk of an association between VDT exposure and pregnancy outcome. This case-control study considered the association between VDT use and the risk of miscarriage. Cases were 508 women admitted for spontaneous abortion to the Clinica Luigi Mangiagalli and a network of obstetric departments in the Milan area. Controls were 1,148 women who gave birth at term to healthy infants on randomly selected days at the same hospitals where cases were identified. No association emerged between VDT exposure and spontaneous abortion, the estimated odds ratio being 1.0 (95% CI: 0.8–1.2). This evidence agrees with studies conducted in different countries by various authors. Am. J. Ind. Med. 32:403–407, 1997. © 1997 Wiley-Liss, Inc.     

Video display terminals and pregnancy. Evaluation of risks by consensus. Report of an INSERM working group

INSERM established a working group to evaluate the effects of VDT work on pregnancy outcome. The group examined all available scientific papers concerning radiation emitted by VDTs, animal experimentation, and epidemiological studies. An estimation of risk was made for each outcome (congenital malformations, spontaneous abortion, stillbirth, premature birth, and low birthweight) according to a decisional algorithm, a method that gives preponderance to epidemiological arguments. On this basis, the group was able to show that the use of VDTs poses no increased risk of congenital anomalies, stillbirth, or premature birth. Consensus evaluation of divergent epidemiological results concluded that VDT work is not a risk factor significantly affecting spontaneous abortions. The risk of low birthweight could not be validly assessed.     

Gestational vaginal bleeding and pregnancy outcome

The relation between vaginal bleeding and pregnancy outcome was examined in a prospective study of 3,531 women seeking prenatal care in New York City from 1975 through 1985. Women were interviewed in the second trimester or later and were followed up at delivery. The frequency of vaginal bleeding during pregnancy was 22%. Few maternal characteristics or exposures were predictive of bleeding, and those that were associated with an increased risk of bleeding were only marginally so. Risk factors included advanced maternal age, previous spontaneous or induced abortion, working during pregnancy, and certain gynecologic conditions (fibroids, cervical inflammation, and ovarian cysts). Severity of bleeding was examined in relation to birth weight and length of gestation at delivery. Light bleeding during pregnancy was not associated with decreased birth weight or with shortened gestation at delivery. Heavy bleeding was associated with a decrease in mean birth weight of about 100 g (p less than 0.05) but was not significantly associated with the risk of low birth weight (odds ratio (OR) = 1.7, 95% confidence interval (CI) 0.9-3.3). Heavy bleeding was associated with preterm delivery among private patients (OR = 6.4, 95% Cl 1.7-23.5) but not public patients (OR = 0.3, 95% Cl 0.1-1.4). First trimester bleeding of any severity was marginally associated with congenital malformations in the offspring (OR = 1.7, 95% Cl 1.0-2.9); the effect was the same for major and minor abnormalities. There was no association between first trimester bleeding and placental complications of pregnancy or the delivery of a stillborn infant.     

Effects of Bariatric Surgery on Maternal and Infant Outcomes of Pregnancy—An Evidence Analysis Center Systematic Review

BackgroundWhile obesity presents specific acute and long-term risks to the pregnant woman and her offspring, the effects of bariatric surgery on pregnancy outcomes are undetermined.ObjectiveA systematic review was performed according to the Academy of Nutrition and Dietetics Evidence Analysis Library process to determine the effects of bariatric surgery on both maternal and infant health outcomes of pregnancy.DesignA comprehensive literature search of PubMed was conducted to identify studies published from years 2000 to 2015 that examined the health effects of pregnancy after bariatric surgery. Experimental studies and observational studies with a control group were included.Main outcome measuresOutcomes of interest were gestational weight gain, maternal complications (ie, gestational diabetes, pre-eclampsia, eclampsia, hypertension, and postpartum hemorrhage), miscarriage and/or stillbirth, cesarean section, birth weight in grams, birth weight in categories (ie, macrosomia, low birth weight, small for gestational age, and large for gestational age), gestational age and preterm birth, infant illness and complications (ie, perinatal death, admission to neonatal intensive care unit, neonatal illness, and congenital malformation rates), and Apgar scores.ResultsThirteen of 246 studies were included. Compared to body mass index–matched controls without surgery, bariatric surgery before pregnancy reduced infant birth weight in grams, with no effect on total maternal gestational weight gain or Apgar scores. Surgery did not increase risk of adverse outcomes, such as miscarriage and/or stillbirth, preterm birth, or infant complications. Effects of surgery on maternal complications, infant birth weight categories, and surgical delivery rates were inconsistent.ConclusionsBariatric surgery is a successful treatment of maternal obesity, but certain surgery-specific risks may exist. More data are needed to determine clinical guidelines. The long-term effects of surgery on pregnancy outcomes are unknown.     

VDTs: field levels, epidemiology, and laboratory studies

As the use of video display terminals (VDTs) has expanded, questions have been raised as to whether working at a VDT affects the risk of adverse pregnancy outcome. A particular focus for these questions has been the very low frequency (VLF) magnetic field produced by a VDT's horizontal deflection coil. VDTs also produce VLF electric fields, extremely low frequency (ELF) electric and magnetic fields, and static electric fields, Ten studies of pregnancy outcome in VDT operators have been conducted in six countries, and with one exception, none has concluded that magnetic fields from VDTs may predispose pregnant operators to spontaneous abortion or congenital malformation. The epidemiologic studies conducted thus far do not provide a basis for concluding that VDT work and adverse pregnancy outcome are associated. Studies of fetal resorptions and malformations in rodents exposed to VLF magnetic fields have produced inconsistent findings. Two laboratories in Sweden that studied mice have reported positive results, one laboratory showing field-related malformations (but not resorptions) and the other showing field-related resorptions (but not malformations). Two Canadian laboratories have reported negative results in rats and mice. Studies of avian embryos have also yielded inconsistent results, but lacking a maternal-fetal placental interface, avian embryos are a questionable model for evaluating human reproductive risks. Finally, VLF electric and magnetic fields measured at the operator position are in compliance with field strength standards and guidelines that have been established around the world.     

Risk indicators of reduction limb defects.

The birth of a child with a reduction limb defect (RLD) was evaluated in relation to vaginal bleeding, threatened abortion, and other complications of pregnancy, placental weight, birth weight, family history, parental age, and the outcome of previous pregnancies. The material consisted of 453 cases of reduction limb defect and an equal number of non-malformed controls matched for time and place. The children were born in Finland during 1964-77. The cases with reduction limb defect without additional malformations were analysed separately. Statistically significant associations were found between the occurrence of reduction limb defect and the following risk indicators: vaginal bleeding, threatened abortion, duration of gestation under 37 weeks, placental weight 400 g or less, birth weight 2500 g or less, and any type of malformation in the relatives. Vaginal bleeding indicated the risk of reduction limb defect to be increased about fourfold; short gestation indicated about twofold risk of reduction limb defect as an isolated malformation. Both low placental weight and low birth weight were associated to a threefold risk of an isolated reduction limb defect. These factors of an abnormal pregnancy indicated even higher risk of reduction limb defect with additional malformations. Preliminary genetic analysis suggests that hereditary factors play no major part in the aetiology of reduction limb defects.     

先天性消化道畸形的影响因素

  目的  探讨先天性消化道畸形的相关危险因素。  方法  于2019年3-4月采用自编问卷对某院2015-2018年住院的消化道畸形患儿（n=54）和同期同科室入院的非消化道畸形患儿（n=60）及其父亲和母亲在孕前及孕期的基本生活情况进行调查。  结果  单因素分析结果显示:性别、孕周、出生体重、母亲年龄、孕期咖啡因、多种维生素的补充、父亲年龄及父亲在孕妇受孕3月前吸烟与先天性消化道畸形的发生有关。Logistic回归分析模型分析结果显示:男性新生儿为消化道畸形的高危因素（OR=7.168,P < 0.001）;孕期多种维生素的补充为消化道畸形的保护因素（OR=0.103,P=0.004）;父亲在孕妇受孕3月前吸烟>5支/d是消化道畸形的危险因素（OR=2.833,P=0.005）。  结论  男性新生儿、父亲在孕妇受孕3月前吸烟>5支/d为消化道畸形的高危因素,母亲孕期多种维生素的补充为消化道畸形的保护因素。     

Paternal occupational lead exposure and congenital malformations.

STUDY OBJECTIVE--The aim was to investigate whether occupational exposure to lead in fathers is associated with congenital malformation in their children. DESIGN--The study was a retrospective case-control study, nested within the wives of men biologically monitored for inorganic lead. Information on pregnancy outcome was obtained from medical registers. SUBJECTS--Cases were defined as wives with malformed child during 1973-82. Three age matched controls were selected for each case from the wives who had given birth during 1973-1983. The final study population was 27 cases and 57 controls. MEASUREMENTS AND MAIN RESULTS--Paternal lead exposure was assessed with blood lead measurements and data obtained from a questionnaire. The response rate was 67% among the cases and 76% among the controls. The odds ratio (OR) of congenital malformation for paternal lead exposure was increased (OR 2.4, 95% confidence interval 0.9-6.5), although not reaching statistical significance. The odds ratios varied from 1.9 to 3.2, when adjusted for one potential confounding variable at a time. CONCLUSIONS--Because of the small numbers and low participation, this study offers limited support for the hypothesis that paternal lead exposure is associated with congenital malformation. Further epidemiological studies on the reproductive hazards of paternal lead exposure are needed.     

Job stress and adverse outcome of pregnancy: a causal link or recall bias?

A case-base study in a population of 214,108 commercial and clerical female workers in Denmark during the period 1983-1985 investigated whether increasing job stress, defined as increasing job demands and decreasing job control, increased the risk of an adverse outcome of pregnancy. Information on the cohort, the outcome of 24,362 pregnancies, was obtained by linkage with nationwide health registers. Six case groups were selected: 1) 2,248 spontaneous abortions, 2) 209 stillbirths or deaths within the first year of life, 3) 661 infants with congenital malformations, 3) 593 preterm deliveries, 4) 587 infants with term low birth weights, 5) 988 infants with light-for-date birth weights, and 6) a random sample of 2,252 pregnancies that constituted the reference group. Information on exposure was obtained by mailed questionnaire. When dichotomized scales on data concerning job demand and control were used, there was an increased relative risk of spontaneous abortion (odds ratio = 1.28, 95% confidence interval (CI) 1.05-1.57) and term low birth weight (odds ratio = 1.46, 95% CI 1.05-2.04) for women experiencing high job stress. For the other case groups, the odds ratios were as follows: congenital malformation, 1.23 (95% CI 0.93-1.63); preterm delivery, 1.03 (95% CI 0.77-1.39); light-for-date birth weight, 1.08 (95% CI 0.83-1.40); and stillbirth/death within the first year of life, 1.42 (95% CI 0.90-2.24). No substantial response bias was found. When occupational titles were used as an exposure matrix, no increased risk was found, except for term low birth weight. Recall bias is one possible explanation. Thus, the results must be interpreted with caution.     

妊娠期接种流感疫苗与不良妊娠结局的Meta分析

目的 系统评价妊娠期接种流感疫苗与不良妊娠结局的关系。方法 通过计算机检索结合手工检索PubMed、Embase、CNKI、VIP、WF等中英文数据库,查找关于妊娠期接种流感疫苗对妊娠结局影响且符合纳入排出标准的随机对照研究或队列研究,检索时限均从建库至2018年12月。由2位研究员筛选文献、提取资料并评价质量后,采用Stata 12.0软件进行Meta分析。结果 共纳入16个研究,共748 259例（试验组:145 980例;对照组:602 279例）。质量评价表明纳入文献质量较高。Meta分析结果显示,自然流产[OR = 0.14,95%CI(0.10,0.18),P＜0.001]、死产[OR = 0.71,95%CI(0.59,0.85),P＜0.001]、先天性畸形[OR = 0.84,95%CI(0.54,1.30),P = 0.427＞0.05]均低于对照组,表明妊娠期接种流感疫苗不会增加自然流产、死产和先天性畸形的风险,并在一定程度上能降低不良妊娠发生率,敏感性分析表明结果可信,Begg’s法所得P值均表明不存在发表偏倚（自然流产:P = 0.466;死产:P = 1.00;先天性畸形P = 0.175）。结论 现有证据未表明母体流感疫苗接种与自然流产、死产和先天性畸形的风险增加有关,妊娠期接种流感疫苗在妊娠结局方面安全性较高,但仍可开展更多高质量研究予以验证。     

A case-control study of maternal smoking and congenital malformations

Summary. We conducted a population-based case-control study to assess the association between maternal smoking during pregnancy and the risk of giving birth to a child with a congenital malformation. Cases were all singleton livebirths with a congenital malformation recorded on the 1984–1986 Washington State Birth Records (n = 3284). The smoking histories of these mothers were compared to a randomly selected group of mothers with a singleton livebirth of a child without a malformation during these same years (n = 4500). When all malformations were taken as a group, there was no association with maternal smoking (relative risk (RR) = l.0, 95% CI 0.9–1.1). However, increased risks were observed for a number of specific malformations, including microcephalus (RR = 2.0, 95% CI 1.0–4.0), cleft defects (RR=1.4, 95% CI 1.0–2.0), and club foot (RR= 1.4, 95% CI 1.0–2.0). We did not find any association with Down's syndrome (RR=0.8, 95% CI 0.5–1.3) or any other malformation. We conclude that maternal smoking during pregnancy may be associated with an increased risk for some malformations.     

职业接触抗癌药对护士生殖结局影响的流行病学研究

目的 探讨护士职业接触抗癌药及其接触水平与不良生殖结局的关系。方法 对北京、天津、包头24所医院873名护士1021次妊娠情况进行了回顾性群组研究,接触组（350名,433次妊娠）孕前及孕期有明确抗癌药接触史,对照组（523名,588次妊娠）孕期及孕前均不接触抗癌药。应用暴露指数评估护士接触抗癌药的水平。结果 接触组自然流产率（14．1％）、先天畸形率（2．82％）及妊娠剧吐发生率（18．9％）、妊娠贫血发生率（10．2％）高于对照组（分别为8．3％、0．76％、12．7％、5．6％）,差异有显著性（P＜0．05）。经Logistic回归分析,调整年龄、吸烟、饮酒等混杂因素后显示,接触抗癌药自然流产（OR．2．29,95％ CI＝1．46－3．59）、先天畸形（OR．3．63,95％CI＝1．07－12．36）及妊娠贫血（OR＝1．77,95％CI＝1．03－3．05）的危险显著增加（P＜0．01,P＜0．05）。护士职业接触抗癌药的接触水平－反应关系的趋势χ^2检验,自然流产及先天畸形均随抗癌药接触水平的增加有增高的趋势,其χ^2值分别为3．86和14．62（P＜0．05,P＜0．001）。结论 护士职业接触抗癌药可导致妊娠并发症（妊娠剧吐、妊娠贫血）及不良妊娠结局（自然流产、先天畸形）的危险增加,其不良妊娠结局随抗癌药接触水平的增高而增加。     

Chemical hair treatments and adverse pregnancy outcome among Black women in central North Carolina

Several studies suggest that toxic chemicals in hair products may be absorbed through the scalp in sufficient amounts to increase the risks of adverse health effects in women or their infants. This case-control study of 525 Black women from three counties in North Carolina who had delivered a singleton, liveborn infant examined whether exposure to chemicals used in hair straightening and curling increased the odds that the infant was preterm or low birth weight. Cases consisted of 188 preterm and 156 low birth weight births (for 123 women, their infant was both low birth weight and preterm). Controls were 304 women who delivered term and normal birth weight infants. Women who used a chemical hair straightener at any time during pregnancy or within 3 months prior to conception had an adjusted odds ratios (OR) of 0.7 (95% confidence interval (CI) 0.4-1.1) for preterm birth and 0.6 (95% CI 0.4-1.1) for low birth weight. Exposure to chemical curl products was also not associated with preterm delivery (adjusted OR = 0.9, 95% CI 0.5-1.8) or low birth weight (adjusted OR = 1.0, 95% CI 0.5-1.9). Despite this failure to find an association, continued search for risk factors to which Black women are uniquely exposed is warranted.     

家族史及环境因素交互作用与子代先天畸形关系的定量研究

目的探讨家族史及环境因素与先天畸形的关系及其交互作用，定量分析可干预因素的预防分值。方法采用病例对照研究设计，选择符合纳入标准的185例先天畸形作为病例组，选择等量的正常儿作为对照组。对病例组和对照组的母亲进行问卷调查及标本检测，数据采用单因素和多因素非条件Logistic回归分析。结果Logistic回归分析有意义的因素为：家族史、孕早期发热、孕早期营养差、负性事件刺激、巨细胞病毒感染，比值比（OR）及其95％可信区间（95％CI）分别为：3．47（1．70～7．06）、2．74（1．17～6．42）、3．07（1．68～5．74）、1．84（1．00～3．37）、3．04（1．61～5．78），先天畸形阳性家族史与上述四个因素之间存在正交互作用，交互作用的超额相对危险度（RERI）分别为2．94、3．88、1．79、3．53；给定条件下可计算出全面控制可干预因素人群预防分值接近10％。结论先天畸形家族史和环境因素间存在正交互作用；采取高危策略可降低人群中先天畸形的患病风险。     

Maternal, delivery, and perinatal characteristics associated with cryptorchidism: a population-based case-control study among births in Washington State

BACKGROUND: The etiology of cryptorchidism is largely unknown. To identify maternal, perinatal, and delivery characteristics associated with cryptorchidism at birth, we conducted a population-based case-control study using Washington State birth certificates linked to birth hospitalization records. METHODS: We identified 2,395 cases of cryptorchidism among male infants born in Washington State during 1986-1996, and, for comparison, we randomly selected four controls per case (N = 9,580), frequency-matched by year of birth. RESULTS: Infant characteristics associated with cryptorchidism included low birth weight (OR = 1.5; 95% CI = 1.3-1.8), small size for gestational age (OR = 1.9; 95% CI = 1.6-2.2), and breech presentation (OR = 1.7; 95% CI = 1.4-2.1). In addition to cryptorchidism, cases were more likely to have another type of congenital malformation (OR = 3.7; 95% CI = 3.2-4.2), particularly digestive (OR = 6.8; 95% CI = 3.7-12.7) or genitourinary (OR = 4.1; 95% CI = 3.0-5.6). Maternal and pregnancy characteristics associated with cryptorchidism included nulliparity (OR = 1.2; 95% CI = 1.1-1.3), maternal smoking during pregnancy (OR = 1.2; 95% CI = 1.1-1.4), and the following pregnancy complications: oligohydramnios (OR = 1.8; 95% CI = 1.3-2.6), placental abnormality (OR = 1.3; 95% CI = 1.0-1.8), and pregnancy-induced hypertension (OR = 1.6; 95% CI = 1.4-1.9). Odds ratios were similar when the analysis was restricted to term infants. CONCLUSIONS: These findings suggest that factors affecting fetal growth and development may increase the risk of cryptorchidism.     

A case-control study of maternal smoking and congenital malformations

We conducted a population-based case-control study to assess the association between maternal smoking during pregnancy and the risk of giving birth to a child with a congenital malformation. Cases were all singleton livebirths with a congenital malformation recorded on the 1984-1986 Washington State Birth Records (n = 3284). The smoking histories of these mothers were compared to a randomly selected group of mothers with a singleton livebirth of a child without a malformation during these same years (n = 4500). When all malformations were taken as a group, there was no association with maternal smoking (relative risk (RR) = 1.0, 95% CI 0.9-1.1). However, increased risks were observed for a number of specific malformations, including microcephalus (RR = 2.0, 95% CI 1.0-4.0), cleft defects (RR = 1.4, 95% CI 1.0-2.0), and club foot (RR = 1.4, 95% CI 1.0-2.0). We did not find any association with Down's syndrome (RR = 0.8 95% CI 0.5-1.3) or any other malformation. We conclude that maternal smoking during pregnancy may be associated with an increased risk for some malformations.     

Congenital malformations and maternal occupation: a registry based case-control study.

OBJECTIVES: To investigate the relations between congenital malformations and maternal occupation during pregnancy with a registry based case-control study. METHODS: Analysis was performed on data derived from the Florence Eurocat registry surveillance programme. The study included cases with isolated conditions, including chromosomal anomalies (n = 1351), cases with multiple anomalies registered during the 1980-91 period (n = 440), and babies with no congenital malformations recognised at birth who were born from 1982 to 1989 and selected as controls (n = 3223). 11 categories were defined, 10 including cases with isolated malformations and one for cases with multiple congenital anomalies. Four categories of maternal occupation were selected for the study. Odds ratio (OR) values were adjusted for maternal origin, maternal and paternal education, number of previous live births, illness during pregnancy, and maternal age when the group of chromosomal anomalies was analysed. RESULTS: A notable and significant association between oral clefts and mothers involved in leather and shoe manufacturing was found (adjusted OR 3.9; 99% confidence interval (99% CI) 1.5 to 9.8) and the risk consistently increased when considering cases with isolated cleft palate separately (OR 5.4; 95% CI 1.8 to 13.4). Moreover, a significant risk was identified for the association between multiple anomalies and textile dye workers (adjusted OR 1.9; 99% CI 1.0 to 3.8). CONCLUSIONS: This study indicates a notable, significant relation between maternal occupation as a pelt or leather worker and orofacial clefts in offspring. This finding is in agreement with the suggested inheritance models. The dilution effect due to studying large and heterogeneous groups of workers and occupations limits the value of the study; but it provides a good example of the use of a large database to search for teratogenic risk with the aid of malformation registries.     

先天畸形影响因素的流行病学研究

目的 探讨先天畸形的影响因素及其作用强度和交互作用，为提出主要干预措施提供依据。方法 在山东省范围内随机抽取374例先天畸形病例进行1：1配比病例对照研究。数据采用单因素和多因素条件Logistic回归分析。结果 先天畸形主要的影响因素为：先天畸形家族史、孕妇知孕周数、孕早期发热、孕期服药、孕早期接触有害物、母亲化程度、孕早期营养、负性事件刺激，OR值分别为3．987，2．483，3．881，3．038，2．968，0．648，0．325，1．252；先天畸形阳性家族史与其它因素之间存在广泛的交互作用。结论 先天畸形的影响因素具有多元性。先天畸形家族史和环境因素间存在正或负相加模型的交互作用。     

The risk of miscarriage and birth defects among women who use visual display terminals during pregnancy

Use of visual display terminals (VDTs) was examined in a case-control study of pregnancy outcome among 1,583 pregnant women who attended three Kaiser Permanente obstetrics and gynecology clinics in Northern California, 1981-1982. We found a significantly elevated risk of miscarriage for working women who reported using VDTs for more than 20 hr per week during the first trimester of pregnancy compared to other working women who reported not using VDTs (odds ratio 1.8, 95% CI: 1.2-2.8). This risk could not be explained by age, education, occupation, smoking, alcohol consumption, or other maternal characteristics. No significantly elevated risk for birth defects was found among working women although odds ratios were 1.4 for both moderate and high VDT exposure, compared with no exposure (95% CI: 0.7-2.7 and 0.7-2.9, respectively). One possible explanation for these findings is that women who had adverse pregnancy outcomes may have overreported their exposures to VDTs and/or women with normal births may have underreported theirs. The findings may also be due to unmeasured factors confounded with high VDT use such as poor ergonomic conditions or job-related stress. That VDTs themselves are hazardous to the pregnant operator remains a possibility. Our results underscore the need for large cohort studies of working women that will provide objective measures of VDT exposures, ergonomic factors, and stress.     

氯丁二烯对女性生殖影响的流行病学研究

对375名接触氯丁二烯女工和930名对照女工的生殖结局进行了回顾性队列研究。使用SAS程序包,采用x~2检验和非条件Logistic回归分析方法。结果表明,氯丁二烯作业女工的自然流产率(10.53％)、低体重儿出生率(14.78％)显著高于对照组(4.47％和8.22％, P<0.01)。控制混杂因素后的OR分别为1.59(95％可信限1.23～2.06)和1.37 (95％可信限1.09～1.72)。氯丁二烯引起的自然流产多发生在怀孕早期。本研究未发现其他生殖异常增多。