Simplicity 7551 vintage sewing pattern, dated 1976.
Maternity Jiffy Dress or Top, Pants and Shorts in Misses' Sizes:
Top-stitched dress or top with drawstring neckline has patch pockets. Dress is 5" shorter than regular length. Pants and shorts with elastic waistline casing have stay of cotton or nylon stretch jersey or a maternity stretch panel can be used.
Size 12:
Bust 34 inches / 86 cm
Waist 26 1/2 inches / 67 cm
Hips 36 inches / 91 cm
Pattern is cut and checked complete; pants pieces are uncut. Pattern envelope has a store stamp, light shelf wear, age tanning.
More vintage maternity patterns here:
http://allthepreciousthings.com/collections/maternity
