Since it is becoming a tradition now to give away push presents, and you're not really sure if your darling wife will like luxury watches or other pieces of jewwelry (especially since you're a little clueless on what she really finds 'nice'), why not give the gift of physical pampering instead?
Rebirth Spa is known to have the distinction of being the first hospital-based spa providing spa services specifically for pregnant and lactating women. It is located at Asian Hospital but its trained masseuses can also do home service.
Another option would be Mom Massage, which also offers pre and post-natal and lactation massages right at the comforts of your own home.
And then, though it doesn't boast of post-natal massages, Sanctuario Spa still offers luxe pampering packages which the wifey can enjoy once she's recovered from the delivery during her 'day off'.
And if these are too pricey for you... ask friends to direct you to their trusted hilots who usually know how to provide comfort to a recovering mom's body. You can even leave your e-mail address here so I can e-mail you the contact number of my masseuse, who tok care of me while I was pregnant and who still manages all the knotted and tense muscles mothering give me.