Simplicity 5493 vintage sewing pattern, dated ca.1964. 

Maternity One-Piece Jiffy Dress or Jumper in Misses' Sizes:

The sleeveless garment features a front V shaped neckline with a snap on vestee. There are darts and a back zipper closing. V. 1 includes large patch pockets. Braid trims the neckline, pockets and vestee. V. 2 neckline is detailed with braid also. The vestee is of a contrasting fabric. 

Size    16:

Bust   36 inches / 92 cm

Waist 28 inches / 71 cm

Hip    38 inches / 97 cm

Pattern is UNPRINTED, factory pre-cut tissue pieces with perforated symbol markings, unused and factory folded.  Envelope has paper tanning, wear and tear around edges, 3 inch side split on one side.

More '60s patterns here:

http://allthepreciousthings.com/collections/1960s