Think of it as like a wedding. In fact many people couple it as their wedding dinner.

Youll be expected to dress semi- formal, but know the host. If they are kinda farmer or you think her family is farmer, youll be in a nicely pressed suit while her dad is wearing a wife beater.

A hong bao is in order. 2-500 depending on how high level the place is and how close you guys are to her. If she has given you hongbao in the past you should match or beat it. Plus it will give you an idea of how much.

As your wife if you will be seated with friends. Geberally groups of freinds will discuss and all give the same amount.

After that just treat it like a wedding. Eat, be bored, maybe have a drink. When the couple come say " gongxi" then screw off.

I went to one of these earlier this year.

it was the cousin of a local friend who had the baby.

it was only family that attended other than me.

I dressed semi-formal and presented a hongbao to the most senior male member of the family, who was the grandfather of the baby.

It was just an elaborate meal with family pictures at the end.

my friend's mother and aunts all spoke a bit of English and asked me lots of questions.

nothing special really, but interesting to see the dynamics of an extended family.

Hongbao.

It is literally like all other events in China. A dinner where people go into a room, eat and leave. 

In Chinese culture, there are a few celebrations when a couple has a baby. Among those are the RED EGGS, naming the baby, the one month old, the 100 days old, the one year old, etc.

100 days after the baby's birth, relatives and friends will send gifts such as clothes, pants, necklace, bracelets for wrists and ankles, tiger shoes, hats for the baby. This is an important day for the baby because 100 days birth celebration represents the wish that the baby will live 100 years, the baby will wear a silver longevity pendant (in Chinese called Longevity Lock) on the neck. The pants will have long fringe on the legs, because the pronunciation of fringe is the same as year in Chinese. And the more fringe the more years.

Dress code will depend on social standing of the couple whose baby is celebrated. Unless indicated by social status, I would not wear coat and tie,m nor bermuda shorts. Nice troussers and shirt would be fine most of the time, and a hongbao with even number of bills (preferably new ones from bank) inside. If a close friend, then inquire about what to bring, some examples were given above.

Otherwise, it would be a dinner, some drinking, and many toast to the baby future, long longivity and good fortune.

I have been to several of these shin-digs in Guangdong.

In addition to the obligatory hong bao (as mentioned earlier 200-500 -which may or may not be returned to you later in whole or part), you should partake in the standard Guangdong 100 day celebration foods. There will be other food also.

Zhu jiao jiang (ginger pork feet) which looks like a bowl of shit but smells and tastes pretty good and some hong dan (red eggs). Also be prepared to knock down a few glasses of bai jiu with grand dad and his mates.

All this is followed by the usual ooohhhh, aaahhhh, soooo cuuute stuff and some photos. Next step, leave while grand ma's friends bag up the leftovers whilst pressuring you and your gf to get married and have a baby.

a further point based on conception, many chinese believe 100 days is actually the one year birthday of the embryo, as much as abortion is rampant, its not polite to say this anymore in public, but this used to be a common reference to the childs life.

Thanks everyone! I will let you know how it goes if I get to go, my boss isn't keen on giving me time off.