Damiana and her husband Abraham, who live in Cothuma, on the outskirts of La Paz in Bolivia, also have two daughters.
As Alberth celebrates his birthday, Damiana tells the WHO: "He is in excellent health.
"His favourite foods are potatoes and rice - but he now eats everything that we eat at home.
'Alberth likes watching me work'
"He can drink from a glass and he tries to eat with a spoon.
"And he has had an MMR vaccine to protect him against measles, mumps and rubella."
She added: "Alberth loves to help me in the shop - although he gets into everything and I'm not sure how much help he is!
"Already he can stand up and walk a few steps, but most of the time he sits watching me work, or crawls around the shop.
"He can say one word - papa. Otherwise he has lots to say, but we can't really understand him!"
Damiana added: "We have decided not to have any more children. Three is quite enough!"
In Bolivia, 54 of every 1,000 children die before their first birthday.
Nine months old
Damiana told the WHO: "Alberth is just about standing up by himself and has started to take small steps.
"He's making lots of different noises - but nothing we can understand yet!"
'He's making lots of noises!'
But Alberth has been sick. Damiana said: "He had a bad cold and diarrhoea a few weeks ago.
"I took him to our doctor who prescribed medicines and oral rehydration salts. Our public health insurance covered the costs of the medication."
Many children fall ill with colds during winter in Bolivia, and it is easy for them to develop into life-threatening pneumonia. But only 49% of under-fives with colds are taken to see a GP, the WHO estimates.
Damiana said the family cannot drink water straight from the tap.
But she added: "We have just joined the local water co-operative which means we now have chlorine added to our water.
"This makes it safe to drink and prepare food with."
Damiana also uses it to bathe Alberth everyday. But she said: "He doesn't like it very much!"
The bathroom in her back yard which she uses is shared with her neighbours.
At six months
Damiana Mamani, told the WHO Alberth was progressing well.
Alberth has received vaccinations against tuberculosis, hepatitis B, polio, diphtheria, whooping cough and tetanus.
Damiana told the World Health Organization: "He weighs 9.1kg and is 70cm tall."
In Bolivia, 6% of infants aged six to 11 months are underweight. The recommended weight for six-month-old boys is between 6.4 and 9.7 kg.
Damiana added: "I'm still breastfeeding, but Alberth is just starting to eat other food like soups, mashed potatoes, carrots, spinach and chicken.
"He loves banana, papaya and apple. He's got quite an appetite."
Alberth has been healthy, but Damiana has had to take him to the clinic once, when he had a fever and a runny nose.
Alberth is starting to eat solid foods
She added: "We recently took Alberth out for a game of football. He's a bit wobbly on his feet but his legs are getting strong.
"It's my husband's dream to teach him to play! I guess it's never to early to start."
Six weeks old
Damiana said: "My husband is very supportive and was especially helpful when I had a bout of flu recently.
"He bathes and takes care of Alberth every evening when he gets home from work."
She added: "I'm relieved I don't have to go back to work yet.
"During the day, my eldest daughter Edith helps me look after Alberth while I get on with my household chores.
"I've also had a lot of support and advice from women in my neighbourhood."
Seven days old
Damiana said the first seven days of her son's life were "exhausting".
"I breastfeed Alberth every two to three hours, and then try to get some rest when he falls asleep.
"But I also have to look after both my daughters and prepare meals for everyone - and I have an awful cold.
"Luckily, my husband is a great help."
She added: "At the health centre, my husband and I received information on family planning.
"We have three children now and don't plan on having any more."
In Bolivia, 20 in every 1,000 babies die in their first week of life from preventable diseases.
Damiana was in labour for only five hours.
'My husband was with me before, during and after the birth'
She told the World Health Organization: "We are both so happy to have a healthy son in the family.
"We have two daughters already and we wanted a baby boy to make our family complete.
"Abraham is thrilled at the idea of playing football with his new son."
Seven months pregnant
Damiana was told at this stage of her pregnancy that she was expecting a baby boy.
She said: "I saw pictures of my baby for the first time when I had an ultrasound scan at the clinic. It was amazing and made me feel even more excited."
Just over two thirds of women in Bolivia attend at least one antenatal visit during their pregnancy.
Pregnant women should have at least four antenatal check-ups during their pregnancy, according to the WHO.
Five months pregnant
The WHO first spoke to Damiana when she was five months pregnant.
She said then: "I consider myself lucky, because we have a health centre in our neighbourhood where I have been receiving antenatal care."
Damiana expects to rely a lot on her older children to help out when the new baby arrives.
Bolivia has one of the worst maternal death rates in Latin America. One in 47 women dies in pregnancy or childbirth.
Around 65% of births in Bolivia are assisted by a skilled assistant such as a midwife, doctor or nurse.
The WHO says all women should have access to such care.
Where the women live
Photos courtesy of the World Health Organization.