Maternal stress has been shown to have detrimental effects to babies in the womb. A survey of relevant studies was published by Emory University.
Prenatal stress and perinatal outcomes—Maternal stress and anxiety during pregnancy has
been associated with:
- shorter gestation & higher incidence of preterm birth
- smaller birth weight and length
- increased risk of miscarriage
Prenatal stress and infant outcomes—Prospective studies have shown that >
maternal stress and anxiety during pregnancy are related to infant outcomes such as:
- temperamental problems and increased fussiness
- problems with attention, attention regulation, and emotional reactivity
- lower scores on measures of mental development
Prenatal stress and child outcomes—A recent large-scale epidemiological study confirmed some of the infant outcomes above and showed associations between prenatal stress and anxiety and:
Granted, not all of these studies showed correlations between the type of stress your wife is put through by her job - some were about natural disasters or emotional stress like death of a family member. Nonetheless, stress hormones pass through directly to the fetus. Lack of sleep also decreases the body's ability to process stress hormones.
So in answer to your question, yes, a mother's crazy work schedule can affect the baby in the womb. As with all scientific studies correlating inputs like stress with outcomes, whether it will or not is not so easy to determine as it will depend on the specific individual characteristics wife and (future) baby.