Objective: To evaluate the impact of smoking and number of previous births on maternal serum levels of α-fetoprotein and free β-subunit of human chorionic gonadotropin (free β-hCG). Methods: The study included 3,252 completed unaffected singleton pregnancies that proceeded beyond 37 weeks’ gestation and resulted with a birth of healthy child. Smoking status of mothers and data concerning gravidity and parity were collected at the sampling date. Serum markers were measured between 13 and 22 gestational weeks, corrected for maternal weight, and converted to multiples of median (MoM) for unaffected pregnancy of the corresponding gestational age. Median MoM values for both markers were examined in relation to both: smoking habits and number of previous births. Results: Smokers had significantly decreased free β-hCG MoM values compared to nonsmokers (p < 0.001). The median levels showed a negative relationship with the number of previous births. The significance of a decreasing trend was proved, both in smokers (p < 0.001) and nonsmokers (p < 0.001). The median maternal serum α-fetoprotein MoM values did not show any significant dependence, neither with regard to smoking (p = 0.65) nor with regard to parity (p = 0.07). Conclusions: The recommendable adjustment of serum markers to smoking habits, especially concerning the free β-hCG levels, would be worthwhile. The evidence of the coexisting influence of parity on serum levels of free β-hCG, both in smokers and nonsmokers, should perhaps be a stimulus for reconsideration of which corrections the screening performance is dependent on.

Objective: To investigate the relationship between unexplained elevated second-trimester free β-human chorionic gonadotropin (β-hCG) levels and pregnancy complications as well as adverse pregnancy outcomes. Methods: The study cohort comprised 2,110 non-smoking women with chromosomal and structurally normal fetuses at low-risk for both Down’s syndrome (risk <1:250) and neural tube defects (maternal serum α-fetoprotein <2.0 MoM). A free β-hCG value of ≧2.0 MoM was used to define the populations with elevated levels of free β-hCG. Descriptive statistics, χ² test, Fisher’s exact test, and logistic regression analysis were used for statistical analysis, and p < 0.05 was considered statistically significant. Results: The mean maternal age of the study group was significantly lower than in controls (27.9 ± 4.3 and 30.6 ± 5.1 years, respectively, p < 0.05), while the proportion of primigravidas was significantly higher compared to that of controls (p < 0.05). After adjustment of the 2 groups according to maternal age and parity, we observed an increased incidence of preeclampsia among women with elevated free β-hCG levels in relation to controls (p < 0.05). However, a logistic regression analysis demonstrated that the free β-hCG level was not a predictor of the occurrence of preeclampsia. No significant relationship was found with the incidence of gestational diabetes, oligohydramnios, polyhydramnios, pregnancy-related hypertension, intrauterine growth retardation, preterm delivery, spontaneous abortion and stillbirths (p > 0.05).

Objective: The purpose of this study was to investigate the efficiency of second-trimester maternal serum screening for Down’s syndrome and open neural tube defects using alpha-fetoprotein and free β-human chorionic gonadotropin as serum markers. Methods: 3,188 women underwent testing between 14th and 22nd week of pregnancy. Of all tested patients, 25.4% were ≥35 years old. A cut-off risk of ≥1:250 for Down’s syndrome and MS-AFP ≥2.0 MoM for open neural tube defect were considered screen-positive. Results: The detection rate for Down’s syndrome was 77.8% (7/9) with 8.2% screen-positive rate (7.9% false-positive rate). When evaluated separately, in patients younger than 35 and in those ≥35 years old, the screen-positive rates were 3.1 and 23.3%, respectively. A total of 52 (1.6%) were found screen-positive for open neural tube defect; 2 cases of encephalocela and 1 case of gastroschisis were confirmed prenatally. Conclusion: The respectable number of cases with trisomy 21 identified in this study confirms that routine mid-trimester screening for Down’s syndrome including MS-AFP, free β-hCG and maternal age is useful in identifying pregnancies at increased risk.