Expert: Walter Hintz - 4/30/2008

Question
QUESTION: Greetings sir, I am a school student studying biology at school and we are currently covering up the human reproductive system.
I have read that it is not advisable for a pregnant women to smoke after pregnancy.Why is that so?

Lastly, how does the contents of the cigarette affect the baby which is protected inside a strong uterus/womb?Am I right to say that these compounds dissolve in the blood, which then travel via the umbilical cord into the foetus?Why does the baby have such weak resistance to htese chemicals?

Thank you
:)

ANSWER: Hi Bhavani;  The biggest problem in pregnant mothers smoking involves an increase in Carbon monoxide in the mother's blood.  AS you know there is a placental barrier between mother and baby but gases can easily pass by diffusion into the fetal blood stream.  CO effects the oxygen carrying capacity of the babies' blood.  There is no resistance to CO.

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QUESTION: Thank you:), so the umbilical cord does not transfer any toxins as such to the baby?And why can't she smoke immediately after giving birth?

Thanks

Answer
Keep in mind the the cord is the avenue of transfer of blood between the mother and the placenta.  Gas exchanges occur in the placenta where the babies capillaries are bathed in maternal blood.  So certainly anything in the mother's blood is carried to the placenta through the umbilicus. Whether toxins are diffused into the babies blood in the placenta depends upon what it is.  CO easily diffuses through.