What must be true regarding gestational age for fetal scalp blood sampling to be performed?

For fetal scalp blood sampling to be appropriately performed, the gestational age must generally be greater than 34 weeks. This requirement is based on the developmental stage of the fetus, as the procedure aims to assess the fetal condition accurately. At this gestational age, the fetal hematological and physiological systems are sufficiently developed to provide reliable blood samples, and the risk-to-benefit ratio of the procedure is generally favorable.

Performing scalp blood sampling before this gestational age can lead to challenges, such as obtaining insufficient or misleading results due to the immature physiology of a younger fetus. Hence, the procedure is typically reserved for later stages in pregnancy when the fetus can better tolerate the stress of the sampling, ensuring that healthcare providers can monitor fetal well-being adequately.