I think take the prenatal package would be cheaper.
There is a famous gynae i know (actually quite many good review online too), he is Dr. Adrian Woodworth. He had clinic at Sengkang & Choa Chu Kang, and he is from TMC.
He do offer a prenatal package about $668 or $688 (exclude GST) and the package include 13-15 times prenatal visit, and 1 or 2 times post natal visit (can't rmb) and also some basic supplement given if i am not wrong.
And if u 1st time visit him (consultation is $80 or $90) and after which u wan to sign the package, and u can offset the 1st time visit by deduct 1 visit from the package (i forgot how it work, or may be they will just refund the 1st visit charge to you after u sign the package). You may call his SK or CCK clinic and ask for detail. Few of my friends' wife are seeing him , very good review.