Do negative thoughts affect a foetus ?
How do most new parents avoid negative thoughts - for example worrying intensely about birth deformities etc ?

2 Answers 2


Studies have shown there are some effects of maternal stress (usually measured by cortisol levels) on both perinatal outcomes (ie, miscarriages, early births, etc.) and on the later development of the child. They tend to show that significant amounts of stress may be harmful, but medium to low levels of stress are good - better than nearly-no stress. They're also not clearly harmful - as anongoodnurse notes, you're not going to cause a birth defect by being stressed. They may have a marginal effect on when the child is born or his/her size, but it's far from the most significant thing that effects your child.

That said, anxiety about childbirth is entirely normal and natural, and there isn't a (pregnant) woman alive who doesn't have some anxiety about her fetus. That's one of the things that defines us as mammals: strong maternal instincts focused on protecting the fetus and child. You shouldn't worry about those feelings, unless they either begin to interfere with your daily routine (such as you can't get out of bed because you're afraid for the fetus) or with your health. Your obstetrician should be monitoring some elements of your health, such as your blood pressure, and any concerns you have on this side should be directed towards her.

If you want to look into this from an academic point of view, Emory's Child Development Project has a good summary on the subject, and several of the references in the paper are good places to begin; Dr. Janet DiPietro from Johns Hopkins, for example, wrote a book on the subject.

If you want a more layman's summary, WebMD has a good piece on the subject, which includes several comments from leading developmental psychologists and perinatal specialists. They also did a review on a layman-aimed book on the subject, Stress Solutions for Pregnant Moms: How Breaking Free From Stress Can Boost Your Baby’s Potential, which could be another resource to consider, including tips for managing your stress.

  • 1
    I think the OP's question was about negative thoughts more than stress, perhaps? Though, like you, I related them. Commented Jan 30, 2015 at 7:47
  • I suppose that wasn't entirely clear to me, but I translated "worry intensely" to something like anxiety disorder - I suppose the OP can clarify if needed :)
    – Joe
    Commented Jan 30, 2015 at 15:22

It's possible that stress (not mere negative thoughts) has an effect, but to what extent is unknown. It is not a major factor at all; rather stress has a vanishingly small influence on fetal development.

Negative thoughts and stress will not cause obvious abnormalities; those are caused by genetic mutations, and they are either spontaneous (in the egg, or an early cell) or inherited. For example, you can read about cystic fibrosis or Turner syndrome to learn about the genetics of inherited diseases.

Everyone has negative thoughts (and stress). Yet normal children have been the norm for many millennia. If your negative thoughts bother you, you should speak to your doctor about them. Meditation and other methods may help decrease stress, but there are no proven ways to decrease negative thoughts in everyone. That is a physchological problem not unique to pregnancy or parenthood.

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    And the flip-side would be true as well: Thinking only positive thoughts and not worrying at all won't prevent birth defects. Thoughts are not a factor.
    – user11394
    Commented Jan 29, 2015 at 3:13

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