Prevalence of neural tube defect in southern Thailand: a population-based survey during 2009–2012

Background

Neural tube defects (NTDs) are a group of congenital malformation of the central nervous system that leads to permanent physical disability and requires lifelong treatment. In Thailand, there have been three published articles on NTDs, all hospital-based studies, which found prevalence of NTDs of 4.8–6.7 per 10,000 live births.

Objective

It was our purpose with this study to determine the prevalence and type of NTDs in southern Thailand through a population-based survey.

Method

Data were obtained through the population-based surveillance during 2009–2012 in three provinces (Songkhla, Phatthalung, Trang) in southern Thailand. Entries in the birth defects registry included all live births, all stillbirths after 24-week gestational age, and termination of pregnancy following the prenatal diagnosis at any gestational age of all congenital anomalies.

Results

During 2009–2012, 148,759 births were registered in the three provinces. Twenty-eight NTD cases were identified, giving an average of 1.88 per 10,000 births (95 % CI 1.20–2.51): 12 cases with anencephaly (42.8 %), 5 with occipital encephalocele (17.9 %), and 11 with myelomeningocele (39.3 %). The birth prevalence per 10,000 births of anencephaly, encephalocele, and myelomeningocele were 0.81, 0.33, and 0.74, respectively. Sixteen (57 %) were detected in live births, and 12 (43 %) were detected by prenatal diagnosis which later resulted in termination of pregnancy.

Conclusions

The prevalence of NTDs based on the population-based study in southern Thailand was low. About 40 % of NTD cases were detected prenatally and later terminated. Hence, examining only registry live births will result in an inaccurately low NTD prevalence rate.     

Etiology and outcome of non-immune hydrops fetalis in southern Thailand

OBJECTIVE: To study the etiology and outcome of non-immune hydrops fetalis in southern Thailand. METHODS: The medical records and videotape recordings of all pregnant women diagnosed with non-immune fetal hydrops, from January 1993 to December 2002 were reviewed. RESULTS: Non-immune hydrops fetalis was documented in 71 cases. The causes of fetal hydrops were identified in 87.3%. Homozygous alpha-thalassemia-1 dominated as the cause of non-immune fetal hydrops (28.2%), followed by structural abnormalities (15.5%) and infection (12.7%). The underlying etiology remained unknown in 9 cases (12.7%). The overall survival rate of non-immune hydrops fetalis cases was 4.2%. Spontaneous regression occurred in 2 cases. Two cases were lost to follow up after initial evaluation. Termination of pregnancy was performed in 47 cases. There were 12 dead fetuses in utero, 2 stillbirths, 5 early neonatal deaths and only 3 cases survived. CONCLUSIONS: Homozygous alpha-thalassemia-1 is the most common cause of non-immune hydrops fetalis in southern Thailand, and the overall prognosis of non-immune hydrops fetalis is poor. We suggest that an effective thalassemia-screening program for prevention and control of homozygous alpha-thalassemia-1 be established in all areas where the alpha-thalassemia-1 gene is prevalent.     

Prenatal diagnosis of thalassemia in Songklanagarind Hospital in southern Thailand

A thalassemia screening program for pregnant women has been established in Songklanagarind Hospital since 1992. After genetic counseling, a total of 5078 pregnant women accepted entry into a screening program for thalassemia. Couples at risk who should receive prenatal diagnosis were 2.8%. Total cases who accepted prenatal diagnosis were 135. Total clinical cases were 40 (29.6%) with achievement by prenatal diagnosis of 33 cases (82.5%). Genetic amniocentesis is the most acceptable method for prenatal diagnosis. Five cases (12.5%) were misdiagnosed due to contamination of maternal blood cells in amniotic fluid cases. Questionable results were reported in 2 cases (5%). Abortion occurred in one case (0.7%). Improvement of surgical technic in prenatal diagnosis reduced the complications and contamination of maternal cells. This program shows the feasibility of prevention and control of thalassemia disease in southern Thailand.     

The relationship of maternal iodine status and neonatal thyrotropin concentration: a study in Southern Thailand

Iodine deficiency disorder (IDD) is a global health problem. Previous studies in Southern Thailand have shown that the prevalence of goiter in schoolchildren is 3-5%, indicating that Southern Thailand is an iodine sufficient area. We conducted a study in pregnant women to determine their iodine status and whether there was an association between maternal urinary iodine excretion (UIE) and the neonatal thyrotropin (TSH) concentration. We recruited 244 pregnant women attending the antenatal clinic at Songklanagarind Hospital. Their mean age was 28.5 +/- 5.3 years (range 15-42) with a mean gestation age of 9.4 +/- 2.7 weeks (range 6-15). Ten ml urine was collected for UIE measurement. All women were delivered at Songklanagarind Hospital. The mean gestational age at delivery was 38.2 +/- 2.1 weeks (range 28-41). The median maternal UIE was 139.5 microg/l with 78 (32%) women having UIE below 100 microg/l. The median TSH of the infants was 4.14 mIU/l (range 0.30-17.89) with 88 (36.1%) of infants having TSH concentration above 5 mIU/l. Logistic regression analysis revealed that the odds ratio of pregnant women with UIE below 100 microg/l giving birth to infants with neonatal TSH above 5 mIU/l was 2.04 (95% confidence interval 1.17-3.66, p = 0.012). In conclusion, our findings demonstrate that 32% of pregnant women have UIE below 100 microg/l, and that UIE below 100 microg/l in pregnant women is associated with neonatal TSH concentration above 5 mIU/l. These findings suggest that iodine deficiency is prevalent in pregnant women in Southern Thailand.     

Pregnancy outcomes amongst thalassemia traits

Objective

To compare the pregnancy outcome between pregnancies affected and not affected by thalassemia trait.

Methods

A retrospective case–control cohort study was conducted on singleton pregnant women who attended antenatal care and delivered at Songklanagarind Hospital. All of the participating thalassemia trait pregnant women were diagnosed based on hemoglobin typing and/or DNA analysis. A ratio of around 1–1 was used to compare their pregnancy outcomes with normal pregnant women.

Results

Seven hundred thirty-nine thalassemia trait and 799 normal pregnant women were included in the study. All of the women were Thai nationals living in the Southern Region of Thailand and nearly all of them had spontaneously conceived. Maternal complication rates of gestational diabetes, preterm birth, antepartum bleeding, postpartum bleeding, shoulder dystocia and puerperal morbidity, and the rates of neonatal complications: macrosomia, fetal weight <2,000 g, intrauterine growth restriction (IUGR), stillbirth, low Apgar score (<7) at 1 and 5 min and NICU admission, were not significantly different between the two groups. The rate of pre-eclampsia, however, was significantly different, with RRs of 1.73 (CI 1.01–3.00).

Conclusion

The thalassemia trait condition did not affect the risk of gestational diabetes, postpartum hemorrhage, stillbirth, preterm birth and puerperal morbidity. However, pre-eclampsia should be warranted especially among nulliparous and high-BMI pregnant women.     

A population-based study of prevalence of Down syndrome in Southern Thailand

Background

Down syndrome (DS) is the most common chromosomal disorder that causes mental retardation. In 2009, a population-based birth defects study was implemented in three provinces in southern Thailand. This study aimed to determine the prevalence of DS in the studied regions, and the proportion of DS fetuses detected by prenatal screening.

Methods

Data were obtained from a population-based surveillance study undertaken during 2009-2013. Entries in the birth defects registry included live births, stillbirths after 24 weeks gestational age, and terminations of pregnancy following prenatal diagnosis. Infants with clinical characteristics of DS had a chromosomal study to make a definite diagnosis.

Results

Of the total 186 393 births recorded during the study period, 226 DS cases were listed, giving a prevalence of 1.21 per 1000 births [95% confidence interval (CI) 1.05-1.37]. The median maternal age was 36.5 years with a percentage of maternal age ≥35 years of 60.6%. Seventy-seven cases (34.1% of all cases) were diagnosed prenatally and these pregnancies were terminated. The prevalence of DS per 1000 births was significantly higher in older women, from 0.47 (95% CI 0.28-0.67) in mothers aged <30 years to 0.88 (95% CI 0.59-1.17) in mothers 30-<35 years (P<0.01), and to 4.74 (95% CI 3.95-5.53) in mothers ≥35 years (P<0.001).

Conclusions

The prevalence of DS significantly increased with maternal age. About 35% of DS cases were detected prenatally and later terminated. Hence, examining only registry live births will result in an inaccurate prevalence rate of DS.