A U.N. conference on Friday agreed to a plan to curb world population growth, including controversial recommendations for sex education at all school levels, confidential contraceptive advice for teenagers, and safer abortions in countries where they are legal. The plan also asks governments to help curb the spread of the AIDS virus, which now infects an estimated 33 million people. The plan is a follow-up to the 1994 Cairo population agreement, which calls for freezing the total population at no more than 9.8 billion by the year 2050. The world population is currently at 6 billion.