Quote from luisHK:
From the link I posted above :
Birth control and intelligence
Among a sample of women using birth control methods of comparable theoretical effectiveness, success rates were related to IQ, with the percentages of high, medium and low IQ women having unwanted births during a three-year interval being 3%, 8% and 11%, respectively.[35] Since the effectiveness of birth control is directly correlated with proper usage, an alternate interpretation of the data would indicate lower IQ women were more prone to misuse of birth control. Another study found that after an unwanted pregnancy has occurred, higher IQ couples are more likely to obtain abortions;[36] and unmarried teenage girls who become pregnant are found to be more likely to carry their babies to term if they are doing poorly in school.[37]
Conversely, while desired family size is apparently the same for women of all IQ levels,[38] highly educated women are found to be more likely to say that they desire more children than they have, indicating a "deficit fertility" in the highly intelligent.[39] In her review of reproductive trends in the United States, Van Court argues that "each factor â from initially employing some form of contraception, to successful implementation of the method, to termination of an accidental pregnancy when it occurs â involves selection against intelligence."[40]