JWT holds Kimberly-Clark's worldwide family care brand accounts, which include Andrex and Kleenex. It will now also oversee the North American and pan-European marketing for its nappy, sanitary and incontinence brands - business worth $200m (£107m).
Ogilvy & Mather retains the personal care accounts in developing and emerging markets in Eastern Europe, Latin America, Asia Pacific, the Middle East and Africa.
Kimberly-Clark is increasing its strategic marketing investments to build its brand equity and market share. The company is the second-biggest nappy manufacturer in the UK, after Procter & Gamble, which makes Pampers.
The slowdown in birth rates has led manufacturers to focus on NPD. Kimberly-Clark has expanded its offering with flushable wipes for children who no longer wear nappies, called Pull-Ups Just for Kids Wipes.
The paper products firm recorded sales of $15.9bn (£8.5bn) in 2005, to which the personal care division contributed $6.3bn (£3.4bn) and the family care division $5.8bn (£3.1bn).