The First Trimester Screening is Used to Detect Chromosomal Abnormalities in Pregnant Women

Between the ۱۱th and ۱۴th weeks of pregnancy, the first-trimester combined screening test is conducted. This test involves nuchal translucency (NT) ultrasound and blood tests to measure levels of pregnancy-associated plasma protein A (PAPP-A) and human chorionic gonadotropin (hCG). The purpose of this test is to assess the risk of chromosomal abnormalities such as Down and Edwards syndromes. PAPP-A is produced by the placenta, with normal levels ranging from ۹۴۳-۱۴۵۵ mU/L at ۱۱-۱۲ weeks and increasing after ۱۳ weeks. On the other hand, hCG levels significantly increase during the early pregnancy, starting from ۵-۵۰ mIU/ml in week ۳ and reaching ۲۰,۰۰۰-۲۰۰,۰۰۰ IU/L by week ۱۰. In addition, ultrasound measurements like NT and crown-rump length (CRL) are taken into consideration. A case series analysis of ۲۱ first-trimester pregnancies showed significant Pearson correlations between various maternal and fetal markers. For example, there was a correlation between maternal age and fetal CRL index (r=۰.۴۵۶, p=۰.۰۳۸) and NT index (MoM) with free β-hCG (MoM) (r=۰.۵۶۷, p=۰.۰۰۰). These correlations highlight the clinical relevance of the first-trimester combined test in stratifying the risk of aneuploidies. However, the small sample size (n=۲۱) might limit the generalizability of the results. This study emphasizes the importance of considering these interrelations when interpreting screening outcomes and stresses the need for larger studies to optimize risk assessment protocols. The first-trimester combined screening, which includes PAPP-A and hCG biomarkers along with NT and CRL ultrasound measurements, offers valuable information for evaluating the risk of chromosomal abnormalities.

کلیدواژه ها:

Women ، Pregnancy ، First Trimester ، PAPP-A ، β-hCG