Increased chance of autism. What all expectant parents should know. Nightly news begins good evening, as suddenly surging ted cruz has set the stage for a potential republican showdown in iowa between two men who enter this race as outsider book ends to the gop mainstream. Several new polls show senator cruz rapidly moving up on donald trump, pitting the two into open political warfare, and presenting a challenge and a dilemma to the party establishment. All coming on the eve of tomorrows next republican debate. Nbcs kasie hunt has the latest. Reporter less than 50 days out from the iowa caucuses, ted cruz is closing in on donald trump, and their unofficial truce officially over. Look at the way hes dealt with the know, frankly, like a little bit of a maniac. Reporter so far, cruz is laughing off trumps attacks, taking to twitter with a link to the famous maniac theme from flashdance. Shes a maniac, maniac trump is still leading in national polls. In iowa, the Des Moines Register poll shows cruz beating him by ten points. What is behind the surge . A sophisticated game in iowa. Long drive. 13 1 2 hours. Reporter theyre joining dozens of volunteers who are so dedicated theyre paying their own way to bunk in a dorm known as camp cruz. You are actually in dorm beds. My husband says lets bunk em. Oh, fantastic. Reporter this is where camp cruz becomes the strike force, getting equipped with tablets that show them which doors to knock on and what to say as they try to convince iowa voters to pick ted cruz. On your support in the caucus . Yes. Reporter but not everyone is sold, and there are signs trumps attacks are hitting home. Theres just a little bit something just about his persona comes across that i havent bought yet. Reporter the gop establishment never saw it coming, the republican nomination fight between two outsiders who have made few friends inside the party. Trump and cruz could be a disaster for the republican party. Its going to be difficult potentially for the party to win over mainstream voters in swing states. Reporter republicans are gathering here in las vegas ahead of the last debate of the year. Also today, donald trump releasing a letter from his doctor saying that if he wins, hed be the healthiest individual ever elected to the presidency. Lester . Kasie, thank you. Now to the stunning turn of events for u. S. Army Sergeant Bowe bergdahl held captive by the taliban for five years after walking away from his base in afghanistan, then finally freed last year in a dramatic and controversial prisoner many called bergdahl a deserter or worse, and now tonight, hes facing a courtmartial as our pentagon correspondent Jim Miklaszewski reports. Reporter held hostage by the taliban for five years, Sergeant Bowe bergdahl could face life in a military prison the army ordered him to face courtmartial for desertion and endangering the safety of his fellow soldiers. 20 minutes out, good grief, im over my head. Suddenly this starts to sink in, i really did something bad. Reporter in his first person account for the podcast serial, bergdahl describes how he walked away from his outpost in eastern afghanistan to warn Army Commanders of leadership problems, but was soon captured by a group of heavily armed taliban fighters. Im not stupid enough to try and knife off a bunch of guys with ak47s. Reporter bergdahl was released in a controversial prisoner swap for five taliban prisoners held at guantanamo bay. President obama welcomed bergdahls parents to the rose garden. Wonderful. Its a good day. Yes, its a today good day. Reporter today bergdahls attorney called the charges against his client excessive. The government had for one thing only, a oneday awol. Reporter the army itself is split over the case. Many believe bergdahl should be punished for putting the lives of his fellow soldiers at risk but the investigator in the case suggests that any jail time for bergdahl would be inappropriate. Bergdahl remains on active duty, no date has been set for his courtmartial. Jim miklaszewski, nbc news, the pentagon. Many americans are on edge following the recent attacks in paris and San Bernardino. In our brand new nbc news wall street journal poll, 40 say the federal governments top priority is National Security and terrorism. That number has more than doubled since april, and 29 say theyre worried that they, or a loved one, a terror attack. But today, for the second time in just over a week, president obama argued that his strategy against isis is working. This time he made those comments in a rare appearance at the pentagon. Last month in november we dropped more bombs on isil targets than any other month since this campaign started. The point is isil leaders cannot hide and our next message to them is simple, you are next. The president was at the pentagon for a meeting with his National Security council. On thursday he will also visit the National Counterterrorism center before traveling to hawaii on friday for christmas vacation. Lets turn now to the missed signs in the San Bernardino terror attack. As of now, screeners do not regularly look at social media for people applying to come to this country on socalled fiance visas but that could change now that we know one of the killers left clues on social media before she came here, but they werent flagged until too late. Pete williams. Reporter well before she applied to come to the united states, officials say, Tashfeen Malik was expressing support for violent jihad on social media, but the u. S. Agencies that reviewed her application for a fiance visa did not know that. Now the Obama Administration is reviewing whether social media for visa applicants should be checked, something Many Employers already do. The social media placed a whole new burden and a whole new set of questions, but not impossible ones to resolve. Reporter heres how the process works, a u. S. Citizen applies for a k1 visa to bring in a fiance from overseas. The name of the foreign applicant is checked against u. S. Terrorism databases and state Department Officers overseas get the applicants fingerprints and check criminal records but surprisingly, even in pakistan where Tashfeen Malik is faceceogase e fe ae ce interview. In the k1 program in cases where theres some issue that needs to be explored. Reporter tonight u. S. Officials say Tashfeen Maliks jihadist messages were not only missed because they werent checked but also because they were sent privately to the Facebook Page of her publicly. Meantime investigators work to build a time line for what malik and syed farook were doing before and after the shooting. There was a moment that a vehicle very similar to that newer model ford excursion, i believe thats what it was, had passed by the dealership. Tonight the chairman of the House Homeland SecurityCommittee Says it will consider a bill to require inperson interviews and social media screenings for visa applicants. Last year the number of fiance visas was about 36,000. Tonight were just winter, but you across much of the country, where its so warm, it feels like spring, and heat records are dropping left and right. 60s and 70s, where last year they were snow. Nbcs dylan dreyer reports on the reason and how long into winter this will last. Reporter just eight days before the official start of winter, a december heat wave has set more than 1,000 record high temperatures across the northeast and midwest. Out west its another story, winter is in full effect, treacherous roads, and packed slopes, but ski resorts back east are the good kind. We really need the temperatures to change, or at least become a little more seasonal so we can get a product out and get the facility open. Reporter by this time last year, upstate new york was already buried by snowstorms. Up to six feet of snow fell in parts of western new york. What a difference a year makes, with no snow so far this december, buffalo broke a 116yearold record. Chilling temperatures have given way to this, record temperatures reaching new highs, 70 in buffalo, and 72 in baltimore. Its like weather whiplash, thanks in part to el nino. What we are seeing this year is a near recordsetting el nino pattern over the pacific ocean, which is transporting very warm air across the reporter with el nino reaching its peak, the country can expect several more weeks of mild temps in the midwest and northeast, and storms out west, but as we approach february, a more typical winter should return. Now here in new york city, it is still 61 degrees after hitting a high of 65 earlier today, and for those of you hoping for a white christmas, im sorry, but it looks like most of the country will not be seeing one this year. Dont worry, it will snow eventually, its just not going to get here in time for christmas. Lester . Dylan dreyer tonight in new york, it happened exactly three years ago today, a massacre of innocents, one of the worst Mass Shootings in our nations history, 20 children, ages 6 and 7, murdered along with six adults at Sandy Hook Elementary School in newtown, connecticut. In the aftermath, there was a sense in this country that something would change, whether it be gun law, better access to Mental Health care or some other solution, but as our Stephanie Gosk reports, hundreds of children have lost their lives to gun violence in this country since that awful day three years ago. Reporter one name on this list would be one too many. Instead at least 555 children under the age of 12 have died from firearms since the shooting at sandy hook school, roughly one child every other day for the last three years. The numbers compiled by nbc news showed children are no safer from guns now than they were before the newtown shooting. Even though overall gun violence in the country has dropped. Varied as they are tragic. Why did this have to happen . Why couldnt it have just been me . Reporter hi vus 10yearold son aaron was killed when two gunmen robbed his business and opened fire. 9yearold tyshawn was murdered because gang members allegedly had a vendetta against his father. 9yearold corbin. Some of the deaths could have been avoided with better gun safety, and with gun sales on the rise, its a focus for some dealers. People have loaded guns in the house are just asking for a problem if they have young children. Reporter bob videns family has owned this gun shop in new jersey since the 70s. He actually helped write the state law requiring a gun lock be sold with every gun. You have to have a license to drive a car. Youre feeling that should extend to gun ownership . I have no problem it should go through some type of training or to go pass a test to make sure theyre qualified. Reporter he is among 84 of americans who support background checks for all gun sales, but legislation on background checks went nowhere in congress. Right now, we are being distracted by cultural debates rather than on the central policy questions that are important to keeping americans safe from gun violence. Reporter still since the newtown shooting, 41 states have passed their own laws strengthening gun regulation, not willing to wait for congress. Evidence that in some places, these faces have broken the gridlock. Stephanie gosk, nbc news, glassboro, new jersey. Still ahead tonight could you be higher risk of autism . What a new study has to say about pregnant women who take antidepressants. Also what youre required to do if youre getting one of these hot holiday fine over 1,000. Were back with news about autism that you need to hear, if you or someone you love are expecting. New study just out today found a troubling connection between mothers who take widely prescribed antidepressants and higher risk at their children developing autism. Reporter in what is a time of great expectation and today a set of scary headlines. New study finds the most commonly prescribed antidepressants, if taken during the second and third trimesters, are associated with an 87 increased risk of autism. But experts say its a big jump of what is still a very small number. For women who are taking antidepressant during pregnancy, they found that they have onehalf of 1 of an increase in having an autistic child. Reporter this is the latest study to link antidepressants to birth defects and developmental delays. The drugs in todays study are called ssris, with brand names such as prozac, paxil and zoloft. One manufacturer says its reviewing the study, which does not conclude these drugs cause autism. Its really just a correlation, not a cause and effect, so Something Else has caused this increase in the group that took antidepressants. Reporter obstetrician joanne stone says she wont tell her patients to stop taking the drugs because untreated depression can be very serious. What are the risks of not taking the medications . The risk of not taking the medication are increased risk for poor pregnancy outcome, higher preterm delivery rates, higher caesarian rates and potentially higher risk for adverse outcome for the babies. Reporter meaning women need to look at all options when deciding whats best for them and their babies. Anne thompson, nbc news, new york. Were back in a moment with why you may not be able to buy a hot holiday gift from one of the retailers. Tonight on this busiest shipping day of the year for both the u. S. Postal service and fedex, news about two of the hottest gifts this amazon has stopped selling several models of the socalled hoverboards over concerns about the risk of fires caused by their lithium ion batteries. The Consumer ProductsSafety Commission is investigating reports of at least 11 such instances, and all of the countrys Major Airlines have banned them from flights. And another item on so many wish lists, drones. If you own one or you plan to give one as a gift, it will have to be registered with the government. New rules at the faa is detailing tonight as the feds try to cut down on the close calls between drones and airplanes, more than 1,000 just this year. Heres nbcs tom costello with more. Reporter its the must have gadget of the year, more than 400,000 drones are expected to be sold over the holidays, a whopping 1. 5 million for all of 2015. Theyve also crashed at sporting events, even on the white house lawn. We just had something fly over us, i dont know if it was a drone or balloon, it just came real quick. Report 100 drone sightings and close calls each month. Now the faa is rolling out new rules that go into effect next monday, all drone owners 13 and older must register their drones online, including name, address, and email. The cost 5, though that will be waived for the first 30 days. We think this is not just about registering. This is also about educating and providing folks with the information they need to do this safely. Dont fly near airports or any manned aircraft. Reporter by registering the drones user also also get the rules, fly below 400 feet, at least five miles from airports. While the drone applauded registration, the model aircraft an unnecessary burden for its members. Youre always going to have a guy that does something stupid. Recently caught up with some drone enthusiasts. Give me a list of five things that the government does well. Theyre going to screw it up. Reporter registering drones will allow authorities to track down owners if they crash in restricted air space. The potential fine tom costello, nbc news, washington. When we come back, its the moment generations of fans have been waiting for. The force awakens. Finally tonight, for a lucky few, the wait is over. Star wars the force awakens is premiering tonight in hollywood. It was a long time ago, way back in 1977, when the original became a force in popular culture. Now all these years later, as our joe fryer reports, the new sequel is the most widely anticipated movie of the year. Reporter in a galaxy far, far away, better known as hollywood oh no reporter star wars lovers are lining up outside the tcl chinese theater. Its like every family reunion. You make time for it, you cant miss it. Reporter some of the fans will have spent 12 days in line. Caroline ritter and andrew porters traveled from australia, before seeing the movie thursday, theyll get married right here, so whats more important . Technically the is just as important. Reporter set about 30 years after return of the jedi the force awakens will introduce a new crop of characters and mark the return of princess leia, now a general, and han solo. Were home. Reporter the movie is expected to earn 1. 5 billion and 2 billion worldwide, maybe more. Incredible numbers, they could be recordbreaking and could be in the top three movies of alltime. Reporter the starstudded World Premiere takes place tonight in hollywood, but when the original movie premiered in 1977, there was little fan. Narrator fare. They were surprised next thing you know we have people wrapped around the block. Reporter somewhere in the horde of moviegoers, 3yearold brendan thibodeau, 30 years later back in line. I cant wait to see it, i cant wait. Its giong to be amazing. Reporter for generations old and new, its clear the force is still with us. Joe fryer, nbc news, hollywood. Night. Im lester holt. For all of us at nbc news, thank you for watching, and good night. The sale of nevadas largest newspaper is shrouded in why wont the new owner come forward . Is debate dep are in las vegas. Many of the candidates are al also tonight, talk about a private party. How about renting out an entire hotel for you and your fnews three live at 6 00 starts right now. Live from las vegas this is news three. Again but the new ownership