t of the embryo, but this can rarely be linked directly with smoking. Another possibility is that smoking affects hormonal systems that sustain pregnancy, for example, progesterone, so that the uterus is unable to support implantation. Tests are being done now to find other reasons smoking may induce abortion. One major factor that is probably paid the most attention to regarding this topic is birth weight. This is because birth weight is a fairly accurate barometer of prenatal development. Another reason is because birth weight is most commonly associated with maternal smoking. The tests involving birth weight have been more successful than those involving spontaneous abortion. Recent studies take into account the sex of the offspring and racial and genetic background. With these factors accounted for, the reductions in birth weight of infants born to smoking mothers range from forty to four hundred and thirty grams less than the birth weights of children born to nonsmoking mothers, with the average being two hundred grams, or seven ounces, less. Also, smoking infants tend to be shorter than nonsmoking infants, approximately 1.4 centimeters shorter, though the major factor is the weight. In some studies, the circumference of the infant's head was significantly reduced, due to maternal smoking. The low birth weight is also affected by the amount of cigarettes smoked a day. Eight percent of women who smoke one cigarette a day have babies with a low birth weight. Infants born to mothers who smoked while they were pregnant tend to remain below normal in height and weight. The lower the birth rate of an infant is, the greater the chance of perinatal mortality, also logically brought about by maternal smokin

Some topics in this essay:
Children Carry, United Five, Death Syndrome, maternal smoking, birth weight, smoking pregnant, spontaneous abortion, born smoking, born smoking mothers, respiratory disorders, smoking babies, cigarettes day, height weight, pregnant women, long-term effects smoking, weight infants born, low birth weight, effects smoking pregnant,