Maria Yu have always associated the number 13 with happiness. She met her husband on May 13, received her passport on April 13, and on Friday, June 13, was reunited with her 74-year-old mother whom she hadn't seen for 31 years.

The emotional reunion at National Airport came after 20 years of letter writing and phone calling to countless Chinese and American officials, and even a visit by Yu's husband Michael to the People's Republic of China in an attempt to get Chen Seu-Su out of Shanghai.

In addition to her daughter and son-in-law, Chen was greeted by four of the six Yu children, whom she had seen only in photographs. Chen had flown from China to Dakar in West Africa to meet her son, his wife, and four grandchildren whom she had never seen. The other two Yu children will arrive this weekend from Huntsville, Ala., and St. Louis, Mo., and the four children of Chen's youngest son, who recently died will fly from Seattle for the reunion. One daughter and her family remain in China.

During the drive back to the Yus' brick rambler home in Beltsville, Chen and her daughter exchanged the mother-daughter chit-chat they had missed out on for three decades.

"I had told my mother years ago that my husband was a little short," Maria Yu related. "You know how mothers want you to marry tall, dark and handsome men."

But one of the first comments Chen made on her arrival was "Your former boyfriends were much shorter!"

Although Chen was equally delighted to see all of her grandchildren, she particularly wanted to meet her grandson, Gerard, a podiatrist living in Philadelphia.

"My mother has foot problems, so she was very happy to learn there was a foot doctor in the family," Yu explained.

"God must have sent him to me," Chen said in Chinese.

Yu moved to Hong Kong six months after the Communists took over in 1949. She had been working for the Catholic Welfare Agency, which transferred to a Hong Kong office when Mao came into power.

"I always told myself, 'I know I'll go back soon,' but I received a scholarship to Catholic University and once you come to America you don't want to leave," she said.

Even so, Yu never imagined that she would be separated from her mother for 31 years.

It was only after the United States established diplomatic ties with the People's Republic that Chen, whose departure from Shanghai was blocked when the Communists took power, was able to leave.

When Chen's son-in-law visited authorities in Peking in May 1979, he obtained the necessary documents for Chen to leave Shanghai for America. But Chen was afraid to leave the confines of the country in which she had lived all her life and waited for her son, a Catholic priest from Chicago, to bring her out of China.

"I hope I live longer now, so I can forget about all those years of loneliness in China," Chen said through her daughter.