Yes. You can shut this off. @Sharonia ,
To turn off random pregnancies: MCCC > MC Pregnancy > Pregnant Sim Selection > Pregnancy Percentage
The 'try for baby' percentage used when testing for random NPC pregnancies. It can be separately set for the Teen, Young Adult, Adult and Elder age groups. A number between 0 and 100 can be specified. 0 will turn-off random pregnancies for NPC's.
To shut off random marriages:
MCCC > MC Pregnancy > Marriage Sim Selection > Marriage Percentage
The percentage chance that random NPC marriage will happen to eligible NPC Sims. It can be separately set for the Teen, Young Adult, Adult and Elder age groups. A number between 0 and 100 can be specified. 0 will turn-off random marriages for NPC sims.
Deaderpool has a great site where you can look up settings & descriptions here:
https://deaderpool-mccc.com/#/Top
Click the turquoise box to look up a specific setting and/or it's description & ui path.