Anemia before pregnancy and risk of preterm birth, low birth weight and small-for-gestational-age birth in Korean women

BACKGROUND/OBJECTIVES

Maternal prepregnancy hemoglobin concentration has rarely been explored as a risk of poor birth outcomes. This study examined whether women with anemia before pregnancy would be at higher risk of preterm birth, low birth weight (LBW) and small-for-gestational-age (SGA) birth.

SUBJECTS/METHODS

This retrospective cohort study was conducted on 70,895 Korean women who delivered a singleton in 1999, with their prepregnancy hemoglobin concentration measured at health examinations in 1997-1999. A logistic model was used to adjust for confounding variables and calculate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

In adjusted analysis, moderate-to-severe anemia (hemoglobin <100 g/l) before pregnancy was associated with preterm birth (OR, 1.53; 95% CI, 1.05-2.23; P=0.027), LBW (OR, 1.81; 95% CI, 1.24-2.64; P=0.002) and SGA (OR, 1.71; 95% CI, 1.35-2.17; P<0.001) when compared with prepregnancy hemoglobin of 120-149 g/l. Mild anemia (hemoglobin of 100-119 g/l) was also associated with LBW (OR, 1.21; 95% CI, 1.06-1.39; P=0.005) and SGA (OR, 1.15; 95% CI, 1.06-1.25; P=0.001). The risk of preterm birth, LBW and SGA across 11 prepregnancy hemoglobin groups depended on the severity of anemia (P for trend=0.042, 0.019, and 0.001, respectively). A high hemoglobin concentration (≥150 g/l), however, was not associated with adverse birth outcomes.

CONCLUSIONS

Anemia, not high hemoglobin concentration, before pregnancy was associated with an elevated risk of preterm birth, LBW and SGA, and the risk increased with the severity of anemia in Korean women.

A comparison of perinatal mortality in Korea on holidays and working days

OBJECTIVE

To examine whether the perinatal mortality of infants born during holidays differs from that of infants born on workdays, and to elucidate its cause.

DESIGN

Cross-sectional study. Setting Vital statistics linked to the National Infant Mortality Survey data for 1999 births in Korea.

POPULATION

In all, 628 485 births in 1999 in Korea.

METHODS

Number of births and perinatal mortality were classified according to the day of the week using the occurrence index. After adjusting for confounding factors, the odds ratios (ORs) for increased holiday mortality were estimated using logistic regression.

MAIN OUTCOME MEASURE

Birthweight-adjusted perinatal mortality.

RESULTS

Births on holidays were 33% fewer and perinatal deaths 24% higher than expected (PMR, Perinatal Mortality Rate, 16.4 versus 12.8; OR, 1.3; 95% CI, 1.2-1.4). After the adjustment of birthweight, gender, plurality and congenital anomalies, the odds ratio for death of infants born during holidays was 1.2 (95% CI, 1.1-1.3).

CONCLUSIONS

The higher perinatal mortality during holidays in Korea appears to be due to different qualities of perinatal care, rather than difference in case-mix.

Effects of smoking on the mortality of lung cancer in Korean men

Few studies have examined the effects of smoking on the morbidity and mortality of lung cancer in Korean men. In Korea, where the prevalence of smoking is among the highest in the world, the morbidity and mortality of lung cancer are rapidly escalating. The objectives of this study were to prospectively examine the effects of smoking on lung cancer and to determine the combined effects of the amount, duration and age that smoking was started. The design was a prospective cohort study with a follow-up period of six years (1993-1998). The subjects included a total of 305,687 Korean men from 35 to 64 years of age who received health insurance from the Korea Medical Insurance Corporation and who had biennial medical evaluations in 1992. The main outcome measures were deaths from lung cancer. As a baseline, 58.2% were current cigarette smokers. Between 1993 and 1998, 891 lung cancer events (34.4/100,000 people per year) occurred. In multivariate Cox proportional hazards models controlling for age, exercise and alcohol use, current smoking increased the risk of lung cancer (risk ratio [RR], 5.6; 95% confidence interval [CI], 4.2 - 7.3). There were significant dose-response relationships to the amount, duration of smoking and age that smoking was started. Compared with nonsmokers, the RR from current smokers who smoked 20 cigarettes per day for over 30 years was 8.2 (5.9 - 11.3), the RR from current smokers who smoked for over 30 years and were less then 19 years of age when they started smoking was 7.8 (5.2 - 11.9), and the RR for those who smoke 20 cigarettes per day and were less than 19 years of age when they started smoking was 8.3 (5.9 -11.6). This study demonstrates that in Korea smoking is a major independent risk factor for lung cancer, and that the risk increases with an increased amount, longer duration, and younger starting age.

A small-scale survey on the status of intestinal parasite infections in rural villages in Nepal

The status of intestinal parasite infections was investigated in two rural villages (Chitrasar, Jerona) in Chitwan District, Nepal in 1999. Stool examination was performed with a total of 300 specimens from schoolchildren by formalin-ether sedimentation technique. The prevalence rate of intestinal parasite infections in the surveyed areas was 44.0%. The prevalence rate in Jerona was slightly higher than that in Chitrasar. The prevalence rate of intestinal parasite infections in female was slightly higher than that in male without statistically significant difference. Entamoeba coli was the most commonly found protozoan parasite (21.0%) followed by Giardia lamblia (13.7%) and others (5.3%). Hookworm was the most prevalent intestinal helminth (13.0%) followed by Trichuris trichiura (3.0%) and others (5.0%). Forty-three specimens (14.3%) showed mixed infections. It is necessary to implement large-scale treatment with anthelminthics, health education and sanitary improvement for intestinal parasite control in the surveyed areas.

Incidence of presbycusis of Korean populations in Seoul, Kyunggi and Kangwon provinces

Presbycusis, a bilateral sensorineural hearing loss caused by changes in the inner ear, is related to multiple factors such as noise exposure and otologic disease. In institute-based studies, we tried to determine the incidence of presbycusis in Korean populations living in Seoul, Kyunggi and Kangwon provinces by gender and age groups. The subjects were people who had visited health promotion centers. Pure tone audiometry was done over 20 years on 6,028 subjects. In a community-based study, the subjects were elderly residents of Kanghwa-do area. There were no obvious factors that could cause hearing impairment in the subjects. For the pure tone audiometry, hearing threshold was obtained by using the six-dimension method. The incidence of presbycusis for subjects aged 65 years and older was 37.8% and 8.3% for > or = 27 dB HL criterion and > or = 41 dB HL criterion, respectively. The incidence increased with age. A statistically significant difference in the hearing threshold was found between men and women aged 65 years or older. No differences were found between the community-based study and the institute- based studies. There was a high incidence (about 40%) of presbycusis among Koreans aged 65 years or older (for > or = 27 dB HL criterion). With an aging population, we anticipate that this report could be used to provide a basic data for the study of presbycusis.

Effects of husbands' smoking on the incidence of lung cancer in Korean women

BACKGROUND

Although smoking remains uncommon among Korean women, lung cancer mortality is rapidly escalating.

METHODS

We investigated the effects of spousal smoking in 160130 Korean women, aged 40-88, who received health insurance from the Korea Medical Insurance Corporation (KMIC). Exposure data were collected during medical examinations conducted between April 1992 and June 1994. The primary outcome variable was the incidence of lung cancer defined by hospital admissions between July 1994 and December 1997. Standardized rates for the incidence of lung cancer were assessed according to the smoking habits of their husbands.

RESULTS

At baseline (n = 160 130), 53.9% of husbands were smokers and 23.3% were ex-smokers, while 1.1% of wives (n = 1756) were current smokers and 0.6% (n = 938) were ex-smokers. During follow-up, 79 cases of lung cancer occurred among non-smoking wives (n = 157436). Wives of heavy smokers were found to have a higher risk of developing lung cancer. The husbands' smoking habits did not affect their wives' risk of developing other cancers such as those of the stomach, liver and cervix, but they did affect breast cancer, which has a significantly higher risk in relation to the longer duration of husbands' smoking. In Poission regression models, adjusting for the age of both husband and wife, socioeconomic status, occupation, residency and vegetable intake, the rate ratio (RR) of lung cancer in non-smoking wives was 1.9 (95% CI: 1.0-3.5) in current smokers and 1.3 (95% CI: 0.6-2.7) in ex-smokers. The RR of lung cancer was 3.1 (95% CI: 1.4-6.6) in wives of husbands who had smoked for 30 years or more compared with wives of non-smoking husbands.

CONCLUSION

In Korea, the incidence of lung cancer is higher among non-smoking women whose husbands smoke, and a dose-response relationship seems to exist.

Smoking and total mortality: Kangwha cohort study, 6-year follow-up

The relationship between smoking and total mortality was examined in a community residents population sample of 2,848 men and 3,543 women aged 55 years or over in Kangwha County, Korea during 1985-1991. A total of 1,436 deaths occurred during a 6-year follow-up among the 1.3 fold-higher in current smokers than in non-smokers among men. The relative risk of total mortality was highest for the 55-59 year old age group both in ex-smokers and in current smokers. PAR for total mortality attributed by smoking were estimated to be 26% for ex-smokers and 25% for current smokers in men. The biggest RR (2.1) and PAR (49%) were observed among those who smoked less than 19 cigarettes per day compared to non-smokers in males. Smokers who began to smoke at age 18 or before showed RR 1.8, and PAR 38% in men. Smoking was the most important variable related with total mortality second only to hypertensiveness not including preventable ones among men in multivariate analyses. Men who began to smoke at nineteen years of age or before had RR 1.5 for total cancer mortality. Women showed the similar picture as males in risk factors composition and in relative risks, with a low association strength, however.