TL;DR: The traditional full-month ceremony is counted by the lunar calendar, on the date one lunar month after birth, but many families today choose a solar date for convenience. The custom of one day earlier for boys and two for girls is a folk convention of holding the ceremony one day before the full-month date for a boy and two days before for a girl; it is not a mandatory rule. The core of the ceremony is giving thanks to the 12 Midwives and celebrating the mother's and baby's good health.
Is the full-month ceremony counted by lunar or solar date?
The full-month ceremony is traditionally counted by the lunar calendar, meaning exactly one lunar month from the birth date. However, many families today choose a solar date for convenience in inviting guests and arranging work. There is no legal regulation or religious doctrine that requires choosing a lunar date, so which calendar to use is up to the family, as long as the meaning of thanksgiving and praying for the child's peace is preserved.
In the lunar calculation, the full-month day is the day that matches the child's birth date in the next lunar month. For example, a child born on the 10th day of the 3rd lunar month has their full-month day on the 10th day of the 4th lunar month. If the child was born on the 30th and the next lunar month is a short month with no 30th, the last day of that month (the 29th) is used. A leap month also counts as a month.
What is the custom of one day earlier for boys and two for girls?
The custom of one day earlier for boys and two for girls is a folk convention for the full-month date: take the date one lunar month after birth, then hold the ceremony earlier, one day earlier for a boy and two days earlier for a girl. For example, a baby born on the 28th day of the 3rd lunar month reaches one full month on the 28th day of the 4th lunar month; by this custom a boy's ceremony falls on the 27th and a girl's on the 26th of the 4th month. Some places, such as Sóc Trăng, follow the saying "gái sụt hai, trai trồi một": girls still two days earlier, but boys one day later, that is, on the 29th of the 4th month. This is an orally transmitted belief with no scientific basis, and not every family applies it.
In folk belief, some say holding it earlier keeps the child healthy and growing quickly; some places explain it as keeping the ceremony from falling on the same lunar day as the child's birth date.
Why is there a difference between regions?
The way of counting the date differs between regions and even between families, because this is an orally transmitted custom.
In the book Việt Nam phong tục, Phan Kế Bính records the custom of Hà Nội city in his day: only at đầy cữ, đầy tháng, and đầy tuổi tôi was a feast offered to the Midwives, with 12 pairs of tiny shoes, 12 betel quids, crab, snail, nham (a mixed salad), and bánh đúc (rice cake)[3]. In the same section, the book gives đầy cữ as seven days for a boy and nine for a girl[3]; it does not mention the custom of one day earlier for boys and two for girls.
What are the offerings for the full-month ceremony?
The full-month offerings usually consist of 12 small portions for the 12 Midwives and one larger portion for the Lady of Reincarnation. Common offerings are glutinous rice, sweet soup, betel and areca, paper shoes, votive paper, and a savory tray for the ancestors.
A Buddhist question-and-answer article advises against killing living beings when a child is newborn, and recommends reciting the Ksitigarbha sutra at childbirth as a prayer[1].
Origin of the belief in the 12 Midwives
The worship of the 12 Midwives has folk origins, tied to the concept of deities who care for pregnancy and newborns. Researchers offer various hypotheses about the origin and meaning of the number 12.
Nguyễn Đổng Chi in Lược khảo về thần thoại Việt Nam states that the legend of the 12 Midwives is now only vaguely known; one theory says they were deities assisting the Jade Emperor from the time of creating humans, another says they were assigned responsibility after the sufficient number had been created[2].
One theory holds that the 12 Midwives are the 12 earthly branches[1]; another view holds that the 12 take turns overseeing childbirth over 12 years, following the 12 zodiac animals[2]. These are folk interpretations and have not been verified.
Milestone ceremonies in the child's first year
Besides the full-month ceremony, Vietnamese people have several other milestone ceremonies in the child's first year, each with its own meaning.
| Milestone | Timing | Main meaning |
|---|---|---|
| Three-day offering to the Midwives (now often called đầy cữ) | 3 days after birth | A tray offered to the Midwives, per Vân đài loại ngữ |
| Đầy cữ according to Phan Kế Bính | 7 days for a boy, 9 for a girl | The mother's confinement ends; she is smoked with salt and rubbed with turmeric before going out |
| Full month | One lunar month | Thanks to the 12 Midwives, celebrates mother and child's good health |
| Hundred days | 100 days | A feast offered to the ancestors, a celebration |
| Thôi nôi, đầy tuổi tôi | One lunar year | A feast offered to the ancestors; some families lay out objects for the child to pick (thử con) |
The book Vân đài loại ngữ by Lê Quý Đôn records: "In our country's custom, three days after giving birth, a tray of rice is offered to the Midwives. On the full-month day, the hundred-day day, and the full-year day, offerings are made to the ancestors and feasts are held"[2].
How do families usually do it today?
Today, each family chooses one of the ways above: the exact date one lunar month after birth, the date moved by the boy-and-girl custom, or a solar date convenient for inviting guests.
Nhật Nguyệt's suggestion: families should choose a ceremony date that suits their practical conditions, as long as they maintain sincerity and the meaning of praying for the child's peace. One should not be overly bound by the custom of moving the date if it causes difficulties in scheduling.
What to note when holding the full-month ceremony
When organizing the full-month ceremony, families should pay attention to a quiet space, avoiding noisy crowds that could affect the newborn. Offerings should be prepared just enough, without ostentation or waste.
Phan Kế Bính also criticized the customs of lying on charcoal and drinking urine during childbirth as unhygienic[3].
