Final answer:
The greatest risk factor for shoulder dystocia in a gestationally diabetic pregnant woman is her condition of gestational diabetes, which can lead to the delivery of a larger baby, increasing the risk of complications.
Step-by-step explanation:
The biggest risk factor for shoulder dystocia in a pregnant woman with gestational diabetes is her condition of gestational diabetes itself. While a tall husband (presumably indicating the potential for a larger baby), advanced maternal age, parity, and family history may contribute to the risk, gestational diabetes significantly increases the likelihood of delivering a larger baby, which can lead to complications such as shoulder dystocia during delivery. Additionally, hypertension and/or diabetes are known to increase the risk of various pregnancy and delivery complications, alongside other lifestyle factors such as obesity, poor nutrition, lack of physical activity, and tobacco use.