gender reveal       
noun [ C ] uk/ˈdʒen.də rɪˌviːl/ us/ˈdʒen.dɚ rɪˌviːl/
 (尚未出生婴儿的)性别揭晓(活动)
an occasion when people are told whether a baby who has not yet been born is a girl or a boy
  She held a gender reveal party at which balloons were burst to shower the guests in pink confetti. 她举办了一个性别揭晓派对,在派对上,气球被戳破,粉红色的纸屑洒在客人身上。 
 Click here to see the funniest reactions to gender reveals. 点击这里查看对性别揭晓的最有趣的反应。 
 - More examples
 - A gender-reveal party is typically held after the first trimester, which is high risk for miscarriage, but before the baby shower, when guests might wish to give gender-specific gifts.
 - The pregnant star shared her gender reveal with fans on her Instagram.
 - Here are some creative gender reveal ideas that will delight your guests.
 - If parents plan to use the gender reveal to discover baby’s gender for the first time themselves, they can have a friend or family member get the results from the doctor.