Final answer:
Avoid the supine position during fetal blood scalp sampling to prevent inaccuracies related to compromised blood flow. The placenta allows exchange of substances, emphasizing the need for pregnant individuals to avoid fetotoxic substances to protect fetal development.
Step-by-step explanation:
When taking a fetal blood scalp sample, the maternal position that should be avoided is the supine position. This position can cause supine hypotensive syndrome, leading to a decrease in maternal blood pressure and thus, potentially, inaccuracies in the sampling process due to compromised uteroplacental blood flow. Moreover, pregnant individuals should be aware of the importance of avoiding fetotoxic substances as these can cross over through the placenta and cause harm to the fetus, leading to abnormalities such as fetal alcohol spectrum disorders (FASD) and issues with development caused by substances such as lead.