Hematologic profiles in twin vs. singleton pregnancies across gestation.

Area of Science:

• Obstetrics and Gynecology
• Hematology
• Maternal-Fetal Medicine

Background:

• Hematologic parameter changes in singleton pregnancies are well-documented, but less is known about twin gestations.
• Prior studies primarily focused on hemoglobin and hematocrit, with limited data on other complete blood count (CBC) values.
• Accurate interpretation of CBCs in twin pregnancies is crucial for clinical decision-making.

Purpose of the Study:

• To compare CBC parameters between twin and singleton pregnancies across three gestational time points.
• To evaluate how CBC values change throughout gestation in both twin and singleton pregnancies.
• To identify distinct hematologic patterns in multifetal gestations.

Main Methods:

• A retrospective cohort study included 419 pregnancies (185 twins, 234 singletons) from 2019-2024.
• Singleton controls were sampled to match twin pregnancies at early (≤14 weeks), mid (>14 to <30 weeks), and late (≥30 weeks) gestational stages.
• Mean CBC values were compared using independent t-tests and adjusted linear regression models; changes from early to late pregnancy were also analyzed.

Main Results:

• Early in gestation, twin pregnancies had higher white blood cell (WBC) counts (9.4 vs. 8.6 × 10³ /µL).
• By mid-pregnancy, twins also exhibited lower hemoglobin, hematocrit, and red blood cell counts.
• In late pregnancy, twin pregnancies showed lower platelet counts (193.9 vs. 206.4 × 10³ /µL) and higher red cell distribution width (13.8% vs. 13.4%).
• WBC counts increased over time in singletons but remained stable in twins.

Conclusions:

• Twin pregnancies demonstrate unique hematologic profiles compared to singletons.
• Elevated WBC counts early in gestation and a more significant platelet decline are characteristic of twin pregnancies.
• These findings underscore the necessity for twin-specific reference ranges in prenatal CBC interpretation.