University of Otago researchers have shed new light on
the damage caused by women smoking while pregnant by showing
severe DNA damage to cells in the placenta.
The research also showed that continued smoking compromised
the cells' ability to repair damage, adding to negative
And the scientists found new evidence that stopping smoking
later during pregnancy greatly reduced the earlier damage,
although it was best not to smoke at all.
The study results will appear in the international journal
Human Pathology next month.
Lead author Dr Tania Slatter, of the Otago pathology
department, said the findings had already been welcomed by
some overseas scientists. Some researchers were ''kind of
amazed that it hadn't been done before''.
Smoking in pregnancy had long been linked to lower
birthweights and increased risk of serious complications, but
the exact mechanisms had been unknown.
''We are particularly excited we now can give people more
detail'' about some of the mechanisms involved.
Otago scientists had identified greatly increased rates of
double-strand DNA breaks in smokers' placental cells. Such
breaks were a severe form of DNA damage that could lead to
cells becoming genetically unstable.
''Our study also showed a clear link between higher rates of
double-strand breaks and lower birthweights and earlier
delivery in mothers who smoked.''
The findings were also likely to help mothers to give up
smoking during pregnancy, or for good.
It had previously been known that smoking during pregnancy
had adverse effects on babies, but researchers previously
could not say in detail ''it affects these cell types'', she
The Otago findings showed clear and specific damage, making
it much harder for people to say ''it's not going to affect
me''. Damage to cells in the placenta was likely to interfere
with the transfer of nutrients from mother to unborn child
and also with important hormone production.
Dr Slatter and her co-authors, including pathologist Dr
Noelyn Hung and obstetrician Dr Celia Devenish, thanked the
families who donated samples of their placentas and the
midwives who supported their study participation. Funding
came from the Healthcare Otago Charitable Trust.
- The findings emerged from an analysis of 236 placenta
samples donated by women in the Otago Placenta Study after
delivery. Of these women, 52 smoked throughout their
pregnancy, 34 gave up smoking four weeks before delivery or
earlier, and the other 150 were non-smokers.