Dear dr what if a pregnant women baby's waist is at down in her 7th month pregnancy?

Please clarify your question.

Perhaps her question is about position of the baby in relation to the birth canal?
'Waist at down' sounds like she's afraid of a breech?

Head down is appropriate. The waist is in the middle of the body.

Yes but what is the best advice for her, at 7 months?

If the concern is baby being breech, for example, bottom first, there are a number of techniques that may encourage baby to rotate. Two common ones are the mother lying in a slant position to bring baby back out of the pelvis, then once upright and walking around, the idea is baby may turn head down, as the head is the heaviest part of baby. Another often successful technique is seeing a chiropractor who is trained in the Webster Technique. I've had several women find success with this for both breech and transverse (side lying) babies.

A doctor or midwife may also consider performing an external version, but this is not done until around 37 weeks and in hospital, and not all care providers will do this.

Hopefully the OP will return and give a bit more information as J_9 requested in case they are referring to something else.