Please explain or write out. It would help me to understand. Thank you. Pregnant
ID: 3304921 • Letter: P
Question
Please explain or write out. It would help me to understand. Thank you.
Pregnant women with gestational diabetes mellitus (GDM) are at risk for long term weight gain and subsequent development of type II diabetes. A pilot weight loss clinical trial was conducted where women with GDM were randomized to either an active intervention using a web-based delivery or control intervention. Women were randomized at 6 weeks postpartum and then were seen at follow up visits at 6 months and 12 months postpartum. At 12 months postpartum, women in the active group lost a mean of 0.2lb with a standard deviation of 15.4lbs. (Ref: Nicklas JM et al, Obstet Gynecol. 201, 124(3):563-70. A web-based lifestyle intervention for women with recent gestational diabetes mellitus: a randomized controlled trial. (5.53) If we assume that the change in weight from pregnancy to 12 months is normally distributed, then what percent of women in the active group were at or above their pregnancy weight at 12 months postpartum? (5.54) At 12 months after postpartum, women in the control group gained a mean of 7.9 lb with a standard deviation of 15.3 compared to their pregnancy weight. If we assume that the change in weight from pregnancy to 12 months is normally distributed, then what percent of women in the control group were at or above their pregnancy weight at 12 months postpartum? (5.55) What are the approximate 10 and 90 percentile of weight changes for pre-pregnancy to 12 months postpartum among women in the active group? Among women in the control group ?Explanation / Answer
Mean ( u ) =0.2
Standard Deviation ( sd )=15.4
Normal Distribution = Z= X- u / sd ~ N(0,1)
5.53)
P(X > 12) = (12-0.2)/15.4
= 11.8/15.4 = 0.7662
= P ( Z >0.766) From Standard Normal Table
= 0.2218
22.18% of women in the active group were at or above their pregnancy weight at 12 months postpartum
5.54)
P(X > 12) = (12-7.9)/15.3
= 4.1/15.3 = 0.268
= P ( Z >0.268) From Standard Normal Table
= 0.3944
39.44% of women in the active group were at or above their pregnancy weight at 12 months postpartum
5.55)
P ( Z < x ) = 0.1
Value of z to the cumulative probability of 0.1 from normal table is -1.282
P( x-u/s.d < x - 0.2/15.4 ) = 0.1
That is, ( x - 0.2/15.4 ) = -1.28
--> x = -1.28 * 15.4 + 0.2 = -19.5359
P ( Z < x ) = 0.9
Value of z to the cumulative probability of 0.9 from normal table is 1.282
P( x-u/s.d < x - 0.2/15.4 ) = 0.9
That is, ( x - 0.2/15.4 ) = 1.28
--> x = 1.28 * 15.4 + 0.2 = 19.9359
10th and 90th percent of weight changes for pre-pregnancy to 12 months postpartum among women in active group