Prenatal Multivitamins bottles have a tamper-evident and childproof cap instead of a foil seal.  

Upon the first time opening the bottle, a security ring will break from around the base of the cap. This will appear similar to the ring that you break when opening a bottle of water.  

If you have the MATERNA + Prenatal DHA combo pack, you will notice that the MATERNA Prenatal DHA bottle has a foil seal. Therefore, in this combo pack, one bottle has a foil seal while the other has a tamper-evident and childproof cap.