I can't say definately for sure what YOU should do. For ME, the Mother-Baby Unit first was incredibly beneficial and if I had to do it all over again, I'd do it all the same way.
Because I spent a few years working with adults, I have had a better transition when having to be pulled to L&D or Mother-Baby once in a while. I don't know about the patients on your hospital's Mother-Baby Unit, but ours had a few patients who were undelivered, too ill to go home but not ill enough to stay in the critical L&D area (beds were more expensive in L&D). Because of this I learned how to take care of Moms who were on bedrest for previa, preterm labor, high blood pressure, etc. We even had two moms who had suffered strokes during their pregnancies! Anyway, I learned a lot from caring for them about finding fetal heart tones, medications they needed, and how to help them cope with the emotional toll bedrest can cause. Not only did this help me relate to the parents who had been on bedrest and had other high risk pregnancies once I was a NICU nurse, the exprience helped me in another way I'd never expected... Once in a while, when working in the NICU, we'd have a low census or L&D would be deperate for help. Sometimes we were required to go to L&D to help for a shift or other times our manager would ask us to volunteer. Well, I had no problem volunteering or going there since the L&D nurses would always give me undelivered patients rather than someone in labor. You see, because of my experience I was able to help out a "sister" unit as well as look good in the eyes of my manager and the L&D manager. The same thing went for Mother-Baby when they were understaffed. I'd help them too sometimes. Also, if I ever needed some overtime and there was none available in the NICU, I could usually get some easily on Mother-Baby and sometimes in L&D.
Basically what I'm saying is that the Mother-Baby experience gave me lots of more options and general calmness/confidence later on in my career in the NICU. Most NICU nurses who had gone straight to NICU from graduation were freaked about having to go to another unit, even Peds! They'd say things like, "I'd rather eat a bug!", "I've not started an IV on an adult since college ____ years ago!", "If I refuse to go can they fire me?" and stuff like that. On the other hand, for me, it was not a problem. I made sure my manager didn't abuse me by making me go every time and she was very good about keeping up with who went last and who's turn it was, etc., but for me being pulled was not a problem like it was for many of the other NICU nurses.
If your Mother-Baby Unit has ante-partum patients, delivered Mom's who's babies are in the NICU, as well as regular, healthy Moms and babies, then I'd say the experience you'd receive there would be similar to what I received. Our Mother-Baby unit held up to 60 moms and 45 babies tops and the hosptial was a 640 bed hospital. We also had a special room for Moms who had delivered but needed to continue to be on Mag Sulate drips for 24 hours after delivery for their high blood pressure. They required hourly checks on many parameters but were very stable... our L&D worked it out with our Mother-Baby Unit to set this up. We were scared at first, but eventually learned how to manage them and that experience was very valuable. My resume now looks much better than it would if I had gone straight to the NICU I believe.
If you're seriously thinking of the Mother-Baby Unit, see if you can check it out somehow. Did you do any clinicals on that unit in school? Do you know anyone who knows someone who works there or knows their manager and what their "scoop" is on the way the department is run?
I can't think of anything else to say right now other than to say that a good Mother-Baby experience could be helpful for more than one reason. I'll also tell you of something I learned from a seasoned nurse and was echoed by many others over the years. The suggestion is to change what you do every 5 to 7 years to keep yourself fresh and motivated. For instance, do Mother-Baby for a year or two and then go to the NICU for 5 years. Join the NICU transport team. Work up to charge nurse if you like. If you feel you need a change you can consider another Maternal-Child area like L&D, Peds, or a GYN floor. Instead of changing units you could end up enjoying being an RN Discharge Planner or Outreach Coordinator working with other hospitals. My point is to keep learning and pushing yourself so you don't end up "stuck" in one place and feeling like you have to stay somewhere just because you've not used your skills in other areas for several years. Just a suggestion....
If you believe in prayer, I'd suggest that too! Whatever "feels" right with be the right thing for YOU to do! Sometimes, when we have to work to hard to get what we think we want, we end up realizing that what we thought we wanted really wasn't what we truly needed at that time. For example: When I graduated from college I wanted to work on Pediatrics because I grew up in the hospital having loads of surgeries and felt comfortable there. Unfortunately my sister was the manager on Peds and I couldn't work under her (hospital rules). I figured the Well Baby Nursery would be the next best thing. I also interviewed in the NICU but was completely overwhelmed with the equipment, buzzers, bells, ventillators, etc. and afraid I couldn't do well there. I prayed about it and decided that if I worked in the Well Baby Nursery first then I could get comfortable with them first and be able to recognize a well baby from a sick baby. I decided to take the Well Baby Nursery job even if the NICU agreed to accept me. I just didn't "feel" ready for the NICU at that time. Then, years later, when I felt I had accomplished and pretty much mastered the Mother-Baby Unit patients, I felt the time was right to challenge myself with the NICU. Sure enough, the time was right and everything fit perfectly. This is what I mean about "if it feels right" to you...
Again, if you feel your hospital's Mother-Baby Unit could offer you a rich experience like I had, and you want to try that for a while, I'd say go for it and do it for a year of two. By then you'd probably be good at baby IV's and routine 3-day antibiotics, drawing blood for certain labs, get good at assessments and Ballards, and probably even get some experience at charging the floor. That helped me as I learned to charge in the NICU years later too. What you learn in one unit can often be applied to another unit. On the other hand, there are many people who know in their hearts from the get go that the NICU is their love and they want nothing else.
One last thought... During our final 3 months of nursing school most of us began looking for jobs. I had worked on a telemetry/medical unit as a student for the last year of my schooling and knew in my heart that I really wanted to work with children. I had kept hearing "Everyone needs 2 years of med-surg before going to a specialty area." I consulted my favorite instructor, the one who taught us L&D, and asked her about that and told her my feelings. She said to me, "Med-Surg experience would be great, but it's not truly necessary this day in time because nearly EVERY area is a specialized area now... I'd rather see you go straight to your babies and be happy than to force yourself into an area you despise and us end up loosing a good nurse who after 2 years of med-surg decides she hates nursing." I took her advice and went to my babies... happily and with a song in my heart. Once I found myself on the Mother Baby Unit (6 months after being hired into the Well-Baby Nursery our unit combined with Postpartum to become the Mother-Baby Unit) I realized how much some med surg could have helped me. ALL kinds of people get pregnant!!! Women with asthma, sickle-cell crisis, mental illness, automobile accidents, needing traction, strokes, gallbladder disease, kidney stones, morbid obesity, drug addicts, alcoholics, you name it!! I see now where the med-surg would have helped. It wasn't necessary but I did have to study a lot at home on my own when I'd encounter these patients. I learned a lot on Mother-Baby. What I truly HATE is when people would say, "Oh you work on Mother-Baby? How nice to rock babies all day and night!" They had absolutely NO idea what all we did there!! If the people in your NICU have that attitude, and you do go to NICU from Mother-Baby, you will most likely have to "prove" yourself, but then again we always have to prove ourselves worthy anytime we accept a new position.
I've talked too much. I don't have any answer for your situation but I do have caring for you and hopes and prayers that you will make the right decision for YOU!
You can do it!!!